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Relevant bibliographies by topics / Enzyme interaction

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Academic literature on the topic 'Enzyme interaction'

Author: Grafiati

Published: 10 September 2022

Last updated: 18 September 2022

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Journal articles on the topic "Enzyme interaction"

1

Gao, Qi, and Dangling Ming. "Protein-protein interactions enhance the thermal resilience of SpyRing-cyclized enzymes: A molecular dynamic simulation study." PLOS ONE 17, no. 2 (February 17, 2022): e0263792. http://dx.doi.org/10.1371/journal.pone.0263792.

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Recently a technique based on the interaction between adhesion proteins extracted from Streptococcus pyogenes, known as SpyRing, has been widely used to improve the thermal resilience of enzymes, the assembly of biostructures, cancer cell recognition and other fields. It was believed that the covalent cyclization of protein skeleton caused by SpyRing reduces the conformational entropy of biological structure and improves its rigidity, thus improving the thermal resilience of the target enzyme. However, the effects of SpyTag/ SpyCatcher interaction with this enzyme are poorly understood, and their regulation of enzyme properties remains unclear. Here, for simplicity, we took the single domain enzyme lichenase from Bacillus subtilis 168 as an example, studied the interface interactions in the SpyRing by molecular dynamics simulations, and examined the effects of the changes of electrostatic interaction and van der Waals interaction on the thermal resilience of target enzyme. The simulations showed that the interface between SpyTag/SpyCatcher and the target enzyme is different from that found by geometric matching method and highlighted key mutations at the interface that might have effect on the thermal resilience of the enzyme. Our calculations highlighted interfacial interactions between enzyme and SpyTag/SpyCatcher, which might be useful in rational designs of the SpyRing.

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Duskey, Jason Thomas, Federica da Ros, Ilaria Ottonelli, Barbara Zambelli, Maria Angela Vandelli, Giovanni Tosi, and Barbara Ruozi. "Enzyme Stability in Nanoparticle Preparations Part 1: Bovine Serum Albumin Improves Enzyme Function." Molecules 25, no. 20 (October 9, 2020): 4593. http://dx.doi.org/10.3390/molecules25204593.

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Enzymes have gained attention for their role in numerous disease states, calling for research for their efficient delivery. Loading enzymes into polymeric nanoparticles to improve biodistribution, stability, and targeting in vivo has led the field with promising results, but these enzymes still suffer from a degradation effect during the formulation process that leads to lower kinetics and specific activity leading to a loss of therapeutic potential. Stabilizers, such as bovine serum albumin (BSA), can be beneficial, but the knowledge and understanding of their interaction with enzymes are not fully elucidated. To this end, the interaction of BSA with a model enzyme B-Glu, part of the hydrolase class and linked to Gaucher disease, was analyzed. To quantify the natural interaction of beta-glucosidase (B-Glu,) and BSA in solution, isothermal titration calorimetry (ITC) analysis was performed. Afterwards, polymeric nanoparticles encapsulating these complexes were fully characterized, and the encapsulation efficiency, activity of the encapsulated enzyme, and release kinetics of the enzyme were compared. ITC results showed that a natural binding of 1:1 was seen between B-Glu and BSA. Complex concentrations did not affect nanoparticle characteristics which maintained a size between 250 and 350 nm, but increased loading capacity (from 6% to 30%), enzyme activity, and extended-release kinetics (from less than one day to six days) were observed for particles containing higher B-Glu:BSA ratios. These results highlight the importance of understanding enzyme:stabilizer interactions in various nanoparticle systems to improve not only enzyme activity but also biodistribution and release kinetics for improved therapeutic effects. These results will be critical to fully characterize and compare the effect of stabilizers, such as BSA with other, more relevant therapeutic enzymes for central nervous system (CNS) disease treatments.

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Yabutsuka, Takeshi, Masaya Yamamoto, Shigeomi Takai, and Takeshi Yao. "Enzyme Immobilization Behavior on the Surface of Hydroxyapatite Capsules under Alkaline Condition." Key Engineering Materials 782 (October 2018): 21–26. http://dx.doi.org/10.4028/www.scientific.net/kem.782.21.

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We prepared hydroxyapatite (HA) capsules encapsulating maghemite particles. In order to evaluate enzyme immobilization behavior of the HA capsules under alkaline condition, we immobilized five kinds of enzymes with different isoelectric point in carbonate/bicarbonate buffer (CBB, pH 10.0). When the enzymes in CBB were moderately charged, immobilization efficiency on the HA capsules showed the highest value. It was suggested that immobilization efficiency was affected according to both pI of enzyme and pH of the surrounding solution and that enzyme immobilized on the HA capsules by not only electrical double layer interactions but also ion interaction and other interactions.

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Grabarczyk, Daniel B., Paul E. Chappell, Steven Johnson, Lukas S. Stelzl, Susan M. Lea, and Ben C. Berks. "Structural basis for specificity and promiscuity in a carrier protein/enzyme system from the sulfur cycle." Proceedings of the National Academy of Sciences 112, no. 52 (December 11, 2015): E7166—E7175. http://dx.doi.org/10.1073/pnas.1506386112.

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The bacterial Sox (sulfur oxidation) pathway is an important route for the oxidation of inorganic sulfur compounds. Intermediates in the Sox pathway are covalently attached to the heterodimeric carrier protein SoxYZ through conjugation to a cysteine on a protein swinging arm. We have investigated how the carrier protein shuttles intermediates between the enzymes of the Sox pathway using the interaction between SoxYZ and the enzyme SoxB as our model. The carrier protein and enzyme interact only weakly, but we have trapped their complex by using a “suicide enzyme” strategy in which an engineered cysteine in the SoxB active site forms a disulfide bond with the incoming carrier arm cysteine. The structure of this trapped complex, together with calorimetric data, identifies sites of protein–protein interaction both at the entrance to the enzyme active site tunnel and at a second, distal, site. We find that the enzyme distinguishes between the substrate and product forms of the carrier protein through differences in their interaction kinetics and deduce that this behavior arises from substrate-specific stabilization of a conformational change in the enzyme active site. Our analysis also suggests how the carrier arm-bound substrate group is able to outcompete the adjacent C-terminal carboxylate of the carrier arm for binding to the active site metal ions. We infer that similar principles underlie carrier protein interactions with other enzymes of the Sox pathway.

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Goldman, Samuel, Ria Das, Kevin K. Yang, and Connor W. Coley. "Machine learning modeling of family wide enzyme-substrate specificity screens." PLOS Computational Biology 18, no. 2 (February 10, 2022): e1009853. http://dx.doi.org/10.1371/journal.pcbi.1009853.

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Biocatalysis is a promising approach to sustainably synthesize pharmaceuticals, complex natural products, and commodity chemicals at scale. However, the adoption of biocatalysis is limited by our ability to select enzymes that will catalyze their natural chemical transformation on non-natural substrates. While machine learning and in silico directed evolution are well-posed for this predictive modeling challenge, efforts to date have primarily aimed to increase activity against a single known substrate, rather than to identify enzymes capable of acting on new substrates of interest. To address this need, we curate 6 different high-quality enzyme family screens from the literature that each measure multiple enzymes against multiple substrates. We compare machine learning-based compound-protein interaction (CPI) modeling approaches from the literature used for predicting drug-target interactions. Surprisingly, comparing these interaction-based models against collections of independent (single task) enzyme-only or substrate-only models reveals that current CPI approaches are incapable of learning interactions between compounds and proteins in the current family level data regime. We further validate this observation by demonstrating that our no-interaction baseline can outperform CPI-based models from the literature used to guide the discovery of kinase inhibitors. Given the high performance of non-interaction based models, we introduce a new structure-based strategy for pooling residue representations across a protein sequence. Altogether, this work motivates a principled path forward in order to build and evaluate meaningful predictive models for biocatalysis and other drug discovery applications.

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Staum, John M. "Enzyme Induction: Rifampin-Disopyramide Interaction." DICP 24, no. 7-8 (July 1990): 701–3. http://dx.doi.org/10.1177/106002809002400709.

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Mokhtar, Nur Fathiah, Raja Noor Zaliha Raja Abd. Rahman, Noor Dina Muhd Noor, Fairolniza Mohd Shariff, and Mohd Shukuri Mohamad Ali. "The Immobilization of Lipases on Porous Support by Adsorption and Hydrophobic Interaction Method." Catalysts 10, no. 7 (July 4, 2020): 744. http://dx.doi.org/10.3390/catal10070744.

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Four major enzymes commonly used in the market are lipases, proteases, amylases, and cellulases. For instance, in both academic and industrial levels, microbial lipases have been well studied for industrial and biotechnological applications compared to others. Immobilization is done to minimize the cost. The improvement of enzyme properties enables the reusability of enzymes and facilitates enzymes used in a continuous process. Immobilized enzymes are enzymes physically confined in a particularly defined region with retention to their catalytic activities. Immobilized enzymes can be used repeatedly compared to free enzymes, which are unable to catalyze reactions continuously in the system. Immobilization also provides a higher pH value and thermal stability for enzymes toward synthesis. The main parameter influencing the immobilization is the support used to immobilize the enzyme. The support should have a large surface area, high rigidity, suitable shape and particle size, reusability, and resistance to microbial attachment, which will enhance the stability of the enzyme. The diffusion of the substrate in the carrier is more favorable on hydrophobic supports instead of hydrophilic supports. The methods used for enzyme immobilization also play a crucial role in immobilization performance. The combination of immobilization methods will increase the binding force between enzymes and the support, thus reducing the leakage of the enzymes from the support. The adsorption of lipase on a hydrophobic support causes the interfacial activation of lipase during immobilization. The adsorption method also causes less or no change in enzyme conformation, especially on the active site of the enzyme. Thus, this method is the most used in the immobilization process for industrial applications.

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Abdi, Sayed Aliul Hasan, Abdulaziz Alzahrani, Saleh Alghamdi, Ali Alquraini, and Adel Alghamdi. "Hexaconazole exposure ravages biosynthesis pathway of steroid hormones: revealed by molecular dynamics and interaction." Toxicology Research 11, no. 1 (December 16, 2021): 60–76. http://dx.doi.org/10.1093/toxres/tfab113.

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Abstract Widespread application of hexaconazole for agriculture purpose poses a threat to human health by disrupting normal endocrine homeostasis. To avoid adverse health effects on human, it is crucial to identify the effects of hexaconazole on key enzymes responsible for steroidal hormone synthesis. In view of this, present study was conducted to investigate the interaction mechanisms of hexaconazole with key enzymes in comparison with their food drug administration (FDA) approved inhibitor by molecular docking and molecular dynamics simulations. Results indicate that hexaconazole contacts with the active site of the key enzymes required for steroidal hormonal synthesis. Results pertaining to root-mean-square deviation, root-mean-square calculation, radius of gyration, hydrogen bonding and solvent accessible surface area exhibited that the interaction pattern and stability of interaction of hexaconazole was similar to enzyme specific inhibitor. In addition, ligand and enzyme complex interaction energy of hexaconazole was almost similar to key enzyme and FDA-approved enzyme specific inhibitor complex. This study offers a molecular level of understanding of hexaconazole with different enzymes required for steroidal hormonal synthesis. Findings of the study clearly suggest that hexaconazole has efficacy to stably interact with various enzyme required to progress the pathway of hormonal synthesis. If incessant exposure of hexaconazole occurs during agricultural work it may lead to ravage hormonal synthesis or potent endocrine disruption. The result of binding energy and complex interaction energy is depicted in the graphical abstract.

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Higgins, G. "Concern over ibuprofen/pancreatic enzyme interaction." Reactions Weekly &NA;, no. 656 (June 1997): 2. http://dx.doi.org/10.2165/00128415-199706560-00001.

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Chadwick, Ben, Derek G. Waller, and J. Guy Edwards. "Potentially hazardous drug interactions with psychotropics." Advances in Psychiatric Treatment 11, no. 6 (November 2005): 440–49. http://dx.doi.org/10.1192/apt.11.6.440.

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Of the many interactions with psychotropic drugs, a minority are potentially hazardous. Most interactions are pharmacodynamic, resulting from augmented or antagonistic actions at a receptor or from different mechanisms in the same tissue. Most important pharmacokinetic interactions are due to effects on metabolism or renal excretion. The major enzymes involved in metabolism belong to the cytochrome P450 (CYP) system. Genetic variation in the CYP system produces people who are ‘poor’, ‘extensive’ or ‘ultra-rapid’ drug metabolisers. Hazardous interactions more often result from enzyme inhibition, but the probability of interaction depends on the initial level of enzyme activity and the availability of alternative metabolic routes for elimination of the drug. There is currently interest in interactions involving uridine diphosphate glucuronosyltransferases and the P-glycoprotein cell transport system, but their importance for psychotropics has yet to be defined. The most serious interactions with psychotropics result in profound sedation, central nervous system toxicity, large changes in blood pressure, ventricular arrhythmias, an increased risk of dangerous side-effects or a decreased therapeutic effect of one of the interacting drugs.

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Dissertations / Theses on the topic "Enzyme interaction"

1

Bruce, Stephen James. "Drug-enzyme interaction through chromatographic profiling." Thesis, Imperial College London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408153.

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Riley, Jane. "The interaction of topoisomerase IV with potential DNA substrates." Thesis, University of Liverpool, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272768.

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Campbell, Robert Stewart. "Trazine dye interaction with the isoenzymes of creatine kinase." Thesis, Open University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254865.

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Jones, G. R. D. "The interaction of the blood clotting factors with cellular components." Thesis, University of Oxford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376932.

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Mmutle, Tsietso Bernard. "Synthesis and interaction of secondary N-nitrosamines with acetylcholinesterase." Thesis, Rhodes University, 1991. http://hdl.handle.net/10962/d1004119.

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Secondary N-nitrosamines: diphenylnitrosamine (DPhNA), dimethylnitrosamine (DMNA), diethylnitrosamine (DENA), dipropylnitrosamine (DPNA), dibutylnitrosamine (DBNA), diethanolnitrosamine (DEtNA), methylnitrosoglycine (MNGly), nitrosopyrrolidine (NPyr), nitrosomorpholine (NMor) and nitrosopiperidine (NPip) were synthesised and their interaction with acetylcholinesterase (AChE) was investigated. Analyses of kinetic results show that DMNA (Ki=34.78 μM); DENA (Ki=54.24 μM); DPNA(Ki=60.36 μM); DBNA(Ki=95.54 μM); DEtNA(Ki=43.68 μM)MNGly (Ki=30.18 μM); NPip (Ki=123 μM); NPyr (Ki=66.07 μM), NMor (Ki=73.93 μM) and DPhNA (Ki=20.32 μM) are competitive and reversible inhibitors of acetylcholinesterase, with respect to the substrate, acetylthiocholine chloride, ATChCl. With time they act as irreversible covalent inhibitors with dipropy1nitrosamine producing 72% inactivation after 60 minutes. Scatchard analyses of f1uorometric titrations, (Kd=0.75mM-4.09mM); gel chromatography (Kd=O. 80mM-4. 60mM) and equilibrium dia1ysis (Kd=O. 71mM- 4.21mM) for MNG1y, DMNA, DEtNA, DENA, DPNA, NPyr, DSNA, NMor and NPip show that these compounds have weaker affinity for the enzyme, as compared to the much tightly binding aromatic DPhNA, Kd values (0.65mM, 0.68mM and 0.68mM) for fluorometric experiments, gel chromatography and equilibrium dialysis respectively. In all cases, the number of binding sites of acetylcholinesterase averaged to four.

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Ngqwala, Nosiphiwe Patience. "Interaction of metallic nanoparticles with biomedical enzyme target: neuronal nitric oxide synthase." Thesis, Rhodes University, 2013. http://hdl.handle.net/10962/d1001536.

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Alzheimer's disease (AD) is the most common type of dementia characterized by intracellular appearance of neurofibrillary tangles, synaptic and neuronal loss; and extracellular accumulation of amyloid-β (Aβ) peptide in senile plaques. The initial causes leading to AD are unknown, and the available treatments are only effective at slowing the degeneration process. The accumulation of arginine in the brain of Alzheimer patients indicates a possible disruption of enzymes responsible for its metabolism. One such enzyme is neuronal nitric oxide synthase (nNOS) and controlling its activity by interacting with nanoparticles may lead to a delay in the onset of the disease. Neuronal nitric oxide synthase was purified using DEAE-Sephacel ion exchange resulting in 10 % yield, 0.43 fold recovery and specific activity 0.09 U/mg. The enzyme was found to be a dimer with a molecular mass of 150 kDa. Characterisation of the nNOS showed an optimum temperature and pH of 50°C and 7.5 respectively, and it was relatively stable at the optimum conditions (t½ = 100 min). The purity was analysed by SDS-PAGE followed by Western blot. Purified nNOS was challenged with 3-7 nm silver and 4-15 nm gold nanoparticles of between synthesized chemical using AgNO3 and either sodium borohydride or sodium citrate. Results showed that gold nanoparticles are more effective at low concentration (5 μM) than silver nanoparticles due to their size difference. Incubation of different concentration of nanoparticles (5, 15, 25, 50 μM) with the purified nNOS showed an initial decrease of 5% in enzyme activity which over time was restored to 80%. This suggests that different nanoparticles are produced in different sizes and interaction over a given time may result in enzyme association–dissociation mechanism. Inhibition studies showed a strong binding of both nanoparticles with Ki values of 1.4 μM and 0.2 μM for silver and gold, respectively. Both nanoparticles inhibited the activity of nNOS extensively as they bound strongly to the inhibition site on the enzyme and were more in contact with fluorophores nanoparticles. This was confirmed by fluorimetry with binding constants of 0.0084 μM and 0.01092 μM for silver and gold, respectively. Results of this study suggest that silver and gold nanoparticles competitively inhibit nNOS.

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Prieto, Luisa Perpetua Simenta Valente Estevez. "Studies of the interaction of selected organic solvents with human liver cytochrome P450." Thesis, University of Sheffield, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310861.

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Peng, YI. "Pyruvate formate lyase and pyruvate formate lyase activating enzyme spectroscopic characteristics, interaction and mechanism /." Diss., Connect to online resource - MSU authorized users, 2008.

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9

Roland, Nathalie. "Interactions des fibres alimentaires avec les enzymes du métabolisme des xénobiotiques chez le rat : hétéroxenise avec une flore humaine." Paris 11, 1994. http://www.theses.fr/1994PA114830.

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Maharjan, Chandra Kumar. "Interaction of Na+/K+ ATPase with Bcl-2 Proteins: Isolated Enzyme vs Epithelial Cell Extracts." Wright State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=wright1464692938.

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Books on the topic "Enzyme interaction"

1

Nycander, Maria. Interaction of cystatins with cysteine proteinases. Uppsala: Sveriges Lantbruksuniversitet, 1998.

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2

Baici, Antonio. Kinetics of Enzyme-Modifier Interactions. Vienna: Springer Vienna, 2015. http://dx.doi.org/10.1007/978-3-7091-1402-5.

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Pang, K. Sandy, A. David Rodrigues, and Raimund M. Peter, eds. Enzyme- and Transporter-Based Drug-Drug Interactions. New York, NY: Springer New York, 2010. http://dx.doi.org/10.1007/978-1-4419-0840-7.

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Cozza, Kelly L. Concise guide to the cytochrome P450 system: Drug interaction principles for medical practice. Washington, DC: American Psychiatric Pub., 2001.

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Pang, K. Sandy. Enzyme- and transporter-based drug-drug Interactions: Progress and future challenges. New York: Springer, 2010.

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6

Invertebrate-microbial interactions: Ingested fungal enzymes in arthropod biology. Ithaca: Comstock Pub. Associates, 1987.

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7

Randall, Richard Christopher. Protein and enzyme interactions in solution and at the silica-water interface. Salford: University of Salford, 1988.

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Mekras, Christos Ioannis. A study of the interactions of enzymes with polyions in aqueous solutions. Salford: University of Salford, 1985.

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9

Raaska, Laura. Cultivation and spawn production of the wood-decaying fungus, shiitake (Lentinula edodes): Optimization of spawn growth, production of degradative enzymes and interaction with wood inhabitants. Espoo: Technical Research Centre of Finland, 1993.

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Giralt, Ernest, Mark Peczuh, and Xavier Salvatella. Protein surface recognition: Approaches for drug discovery. Chichester, West Sussex: John Wiley & Sons, 2011.

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Book chapters on the topic "Enzyme interaction"

1

Keleti, T. "Energetic Consequence of Dynamic Enzyme-Enzyme Interaction." In The Organization of Cell Metabolism, 165–68. Boston, MA: Springer US, 1986. http://dx.doi.org/10.1007/978-1-4684-5311-9_15.

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Zimmerman, Andrew R., and Mi-Youn Ahn. "Organo-Mineral–Enzyme Interaction and Soil Enzyme Activity." In Soil Enzymology, 271–92. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-14225-3_15.

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Bünning, Peter. "Drug–Drug Interaction: Enzyme Induction." In Drug Discovery and Evaluation: Safety and Pharmacokinetic Assays, 975–87. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-25240-2_43.

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Dudda, Angela, and Gert Ulrich Kuerzel. "Drug–Drug Interaction: Enzyme Inhibition." In Drug Discovery and Evaluation: Safety and Pharmacokinetic Assays, 989–1004. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-25240-2_44.

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Li, Albert P. "Drug–Drug Interaction – Enzyme Induction." In Drug Discovery and Evaluation, 543–50. Berlin, Heidelberg: Springer Berlin Heidelberg, 2006. http://dx.doi.org/10.1007/3-540-29804-5_27.

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Dudda, Angela, and Gert Ulrich Kürzel. "Drug–Drug Interaction – Enzyme Inhibition." In Drug Discovery and Evaluation, 551–57. Berlin, Heidelberg: Springer Berlin Heidelberg, 2006. http://dx.doi.org/10.1007/3-540-29804-5_28.

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Eckstein, Fritz. "Interaction of Restriction Endonucleases with Phosphorothioate DNA." In Enzyme Dynamics and Regulation, 200–205. New York, NY: Springer New York, 1988. http://dx.doi.org/10.1007/978-1-4612-3744-0_24.

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Hannon, Bruce, and Matthias Ruth. "Chance-Cleland Model for Enzyme-Substrate Interaction." In Dynamic Modeling, 80–82. Berlin, Heidelberg: Springer Berlin Heidelberg, 1994. http://dx.doi.org/10.1007/978-3-662-25989-4_9.

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Hannon, Bruce, and Matthias Ruth. "Chance-Cleland Model for Enzyme-Substrate Interaction." In Dynamic Modeling, 80–82. New York, NY: Springer US, 1994. http://dx.doi.org/10.1007/978-1-4684-0224-7_9.

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Hannon, Bruce, and Matthias Ruth. "Chance-Cleland Model for Enzyme-Substrate Interaction." In Dynamic Modeling, 129–32. New York, NY: Springer New York, 2001. http://dx.doi.org/10.1007/978-1-4613-0211-7_9.

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Conference papers on the topic "Enzyme interaction"

1

Bolognani, Lorenzo, Michele Costato, and Marziale Milani. "Low-energy laser-ATPase enzyme interaction: theory and experiment." In Europto Biomedical Optics '93, edited by Kazuhiko Atsumi, Cornelius Borst, Frank W. Cross, Herbert J. Geschwind, Dieter Jocham, Jan Kvasnicka, Hans H. Scherer, Mario A. Trelles, and Eberhard Unsoeld. SPIE, 1994. http://dx.doi.org/10.1117/12.169116.

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DePoli, Patricia, Theresa Bacon-Baquley, and Daniel A. Walz. "THROMBOSPONDIN INTERACTION WITH PLASMINOGEN." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643824.

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Platelet thrombospondin (TSP) interacts with plasminogen in a specific and saturable manner. TSP can form a trimolecular complex with histidine-rich glycoprotein and plasminogen and the plasminogen within such complexes can reportedly be activated by tissue plasminogen activator. We have studied the interaction of TSP with plasminogen using Western blotting of plasminogen, reduced plasmin and the elastase-generated fragments of plasminogen and their binding of iodinated TSP. TSP was found to specifically bind to plasminogen and the heavy (non-enzyme) chain of plasmin in a calcium-independent manner. Binding could be blocked by preincubation of the immobilized plasminogen or plasmin with an excess of unlabeled TSP. Plasminogen domains (kringles) were generated by limited eTastase proteolysis. TSP bound specifically to a single 51 kDa plasminogen fragment. The elastase-generated fragments were separated by lysine-Sepharose chromatography and their identities established by amino acid composition and amino-terminal sequence analysis. The 51 kDa plasminogen fragment bound to lysine-Sepharose and had an amino-terminal sequence corresponding to kringle 4 (K4) and a composition consistent with that of K4-K5-plasmin. TSP binding to this fragment was not blocked by the presence of an excess of the fragment K1-K2-K3, K4, nor miniplasminogen (K5-plasmin). Binding does not appear to be directly dependent upon the specific high-affinity lysine binding site of the 51 kDa fragment. Our data suggests that thrombospondin interacts with plasminogen at a single distinct site, and that this recognition site is at or near the K4-K5 contiguous region of plasminogen.

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Bashkov, G., T. Kalishevekaya, and S. Strukova. "ALTERED INTERACTION OF THROMBIN AND ANTITHROMBIN III WITH THE VASCULAR WALL." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643344.

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The role of the endothelial injury in the development of the thrombophylic state was studied in rats with nephrotic syndrome (NS,Heymann nephritis).There were a 6-fold increase of the soluble fibrin concentration and a 30% decrease of plasma antithrombin III (AT) activity in the NSIt was found that the plasma half-life of 125 J-labelled α-thrombin (10-7 M) is 3,0 ± 0,6 min in control animals and 4,0 ± 0,1 min in NS rats. At 20 min following the administration of bovine 125J-thrombin it was observed that in normal animals 84% of the radiolabelled enzyme was bound with vessel wall.while in NS rats the figure was only 63% (p< 0,05). The alteration of thrombin binding to the vascular wall lead to an increase in the amount of soluble fibrin-monomer and AT-proteinase complexes.AT-thrombin complexes and a proteolytically modified form of AT (Mr<68 kDa) were isolated from NS rats plasma by affinity chromatography on heparin-sepharose and chromatofocusing.At 3 min following injection of a 100-fold molar excess of bovine AT (1,7 .10-5 M) it was observed that 35% of thrombin reversibly bound to the endothelium could be detected in the circulation of normal rats. The same excess of AT induced only a 10% (p<0,001) release of 125J-thrombin to the blood stream in the NS rats through the formation of 125 J-thrombin complexes with Mr≥100 kDa.It is being proposed that injury of the vascular wall in the NS animals facilitated the interaction of the enzyme with the substrate (fibrinogen) and inhibitor (AT), and leads to ineffective inactivation of thrombin bound to the endothelium by AT.

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Dzichenka, Yaraslau, Michail Shapira, Sergei Usanov, Marina Savić, Ljubica Grbović, Jovana Ajduković, and Suzana Jovanović-Šanta. "NOVEL LIGANDS OF HUMAN CYP7 ENZYMES – POSSIBLE MODULATORS OF CHOLESTEROL BLOOD LEVEL: COMPUTER SIMULATION STUDIES." In 1st INTERNATIONAL Conference on Chemo and BioInformatics. Institute for Information Technologies, University of Kragujevac, 2021. http://dx.doi.org/10.46793/iccbi21.435d.

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Our in vitro studies showed that a couple of perspective steroidal derivatives showed previously biomedical potential via enzyme inhibition, receptor binding or antiproliferative effect against the cancer cells of reproductive tissues are able to bind to human CYP7 enzymes – key enzymes taking part in hydroxylation of cholesterol, 25-, 27-hydroxycholesterol and a number of steroidal hormones. In silico screening of binding affinity of the modified steroids toward CYP7 enzymes showed that interaction energy for the new ligands is comparable with consequent values, calculated for the ‘essential’ substrates of the enzymes – cholestenone (CYP7A1) and DHEA (CYP7B1). However, no correlation between binding energy and the affinity of the ligand was found. Novel ligands interact with conserved amino acids taking part in stabilization of natural substrates of CYP7 enzymes. A couple of structural features, governing ligand binding, were identified. Among which are planar structure of A-ring for CYP7A1 ligands, absence of many polar fragments in side-chain and presence of polar group at C3 position. Analysis of the docking results showed that CYP7B1 higher selectivity in comparison with CYP7A1 is connected by the structure of the cavity formed by α-helices I and B`. The data obtained will be used for the explanation of ligand specificity of human sterol- hydroxylases.

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Asakura, S., N. Yoshida, and M. Matsuda. "MONOCLONAL ANTIBODIES AGAINST THROHBIN-ANTITHROMBIN III COMPLEX: EPITOPE SPECIFICITY AND EFFECT ON THROMBIN-ANTITHROMBIN III INTERACTION." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643673.

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Among monoclonal antibodies (MCA´s) raised against human thrombin (T)-antithrombin m (AT) complex (TAT), two MCA´s designated as JITAT-16 and 17 with high affinity, Kd = 4.6nMand 4.1 nfi, respectively, were selected and characterized for specificity and functions. Their respective immunoglobulin subclasses are IgGi and IgG2a, and epitopes were found to be different from each Dther as shown by crisscross inhibition experiments. Immuno-alotting of normal plasma and serum electrophoresed on non-SDS aolyacrylamide gel showed that these antibodies reacted with normal serum but not with plasma. This was verified by an anzyme-linked differential antibody immunosorbent assay using aither one of the MCA´s as the first antibody and the other MCA labeled with peroxidase as the second one. By immunoblotting after SDS-PAGE, we found that both antibodies reacted with TAT, nut not with its respective nascent constituent, AT or T. However, they reacted with reactive site-cleaved AT (or thrombin-nodified AT, ATM) and also a complex of AT with activated factor K (Xa-AT). These results indicate that both of these antibodies recognize enzyme-treated forms of AT, including AT molecules :omplexed with enzymes reversibly or irreversibly as well as ATM. Jpon incubation of T with AT in the presence of JITAT-16, T activity remained nearly unchanged and formation of irreversible rAT did not proceed as expected. Moreover, AT was preferentially :onverted to ATM. When JITAT-16 was added after completion of FAT formation, however, neither recovery of T activity nor generation of ATM was observed. These findings were not obtained vhen JITAT-17 had been substituted for JITAT-16. These data suggest that JITAT-16 may have converted AT from an inhibitor to a substrate for T after having recognized a possible intermediate reversible complex of AT with T. Undoubtedly, in the presence of a polyclonal antibody against AT, neither TAT formation nor ATM neneration was observed at all. The mechanism of the unique Function of JITAT-16 has not been fully clarified as yet, but this antibody seems to give us new information on the kinetic study of TAT formation and ATM generation when AT was allowed to react with enzymes.

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6

"Virtual Screening the Interaction of Various Compound from Indonesian Plants with the HGXPRT Enzyme to Find a Novel Antimalarial Drug." In The 3rd International Conference on Life Sciences and Biotechnology. Galaxy Science, 2021. http://dx.doi.org/10.11594/nstp.2021.0805.

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7

Yakubovskaya, A. I., I. A. Kameneva, S. V. Didovich, I. I. Smirnova, N. A. Kashirina, and M. V. Ermolaeva. "Influence of microbial preparations on the enzymatic activity of Thymus vulgaris L." In CURRENT STATE, PROBLEMS AND PROSPECTS OF THE DEVELOPMENT OF AGRARIAN SCIENCE. Federal State Budget Scientific Institution “Research Institute of Agriculture of Crimea”, 2020. http://dx.doi.org/10.33952/2542-0720-2020-5-9-10-119.

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Recently, special concern has been shown to common thyme (Thymus vulgaris L.), essential oil of which has a valuable ingredients and is of interest for different uses. The purpose of the research was to study the influence of polyfunctional microbial preparations on the enzymatic activity of T. vulgaris, which is grown under conditions of the foothill zone of the Crimea. In field experiments on southern Chernozem, we studied the influence of “Biopolycid” and “Cyanobacterium consortium” preparations on the activity of catalase and polyphenol oxidase enzymes in leaves of T. vulgaris. The microbial preparations were spread onto the top layer of the soil once at the stem-extension stage. In this case, their use promoted efficient plant-microbial interaction, i.e. induction of antioxidant enzyme activity, increasing stress resistance of plants. Thus, in the foothills of the Crimea, according to the results of the first year of research, it was proved that top-soil dressing with polyfunctional microbial preparations “Biopolycid” and “Cyanobacterium consortium” increased the enzymatic activity of T. vulgaris plants

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Suttie, W. J., A. Cheung, and M. G. Wood. "ENZYMOLOGY OF THE VITAMIN K-DEPENDENT CARBOXYLASE: CURRENT STATUS." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643991.

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The vitamin K-dependent microsomal carboxylase converts glutamyl residues in precursor proteins to γ-carboxyglutamyl (Gla) residues in completed proteins. The enzyme activity is present in significant activities in most non-skeletal tissues but has been studied most extensively in rat and bovine liver. Early studies of the enzyme utilized bound precursors of vitamin K-dependent clotting factors as substrates for the enzyme and demonstrated that the enzyme requires the reduced form of vitamin K (vitamin KH2), O2, and CO2. Subsequent investigations have taken advantage of the observation that the enzyme will carboxylate low-molecular-weight peptide substrates with Glu-Glu sequences. Utilizing a substrate such as Phe-Leu-Glu-Glu-Leu, it has been possible to demonstrate that γ-C-H release from the Glu residue of a substrate is independent of CO2 concentration. The formation of vitamin K 2,3-epoxide can also be demonstrated in a crude microsomal system, and it can be shown that the formation of this metabolite can be stimulated by the presence of a peptide substrate of the carboxylase. These observations have led to the general hypothesis that the mechanism of action of the enzyme involves interaction of vitamin KH2 with O2 to form an oxygenated intermediate that can interact with a substrate Glu residue to abstract a γ-hydrogen and in the process he converted to vitamin K epoxide (KO). The current evidence suggests that, either directly or indirectly, removal of the γ-C-H results in the formation of a carbanion at the γ-position of the Glu residue which can interact with CO2 to form Gla. The Glu residue intermediate which is formed can be demonstrated to partition between accepting a proton in the media to reform Glu, or interacting with CO2 to form Gla. Current data do not distinguish between the direct formation of a carbanion coupled to proton removal, or the participation of a reduced intermediate. Recent studies have demonstrated that the enzyme will carry out a partial reaction, the formation of vitamin K epoxide, at a decreased rate in the absence of a Glu site substrate. Epoxide formation under these conditions has the same for O2 as the carboxylation reaction and is inhibited in the same manner as the carboxylation reaction. In the presence of saturating concentrations of a Glu site substrate and C02, the ratio of KO formed, γ-C-H released, and C02 formed is 1:1:1. However, KO formation can be uncoupled from and proceeds at a higher rate than γ-C-H bond cleavage and Gla formation at low Glu site substrate concentrations. At saturating concentrations of CO2, Gla formation is equivalent to γ-C-H bond cleavage, and this unity is not altered by variations in vitamin KH2 or peptide substrate concentrations. Natural compounds with vitamin K activity are 2-Me-l,4-naphthoquinones with a polyprenyl side chain at the 3-position. Studies of vitamin K analogs have demonstrated that a 2-Me group is essential for activity but that the group at the 3-position can vary significantly. Modification of the aromatic ring of the naphthoquinone nucleus by methyl group substitution can result in alterations of either the rate of the carboxylation reaction or the apparent affinity of the enzyme for the vitamin. Studies of a large number of peptide substrates have failed to reveal any unique primary amino acid sequence which is a signal for carboxylation. However, current evidence from a number of sources suggests that a basic amino acid rich "propeptide" region of the intracellular form of the vitamin K-dependent proteins is an essential recognition site for the enzyme. This region of the precursor is lost in subsequent processing, and the manner in which it directs this posttranslational event is not yet clarified. Supported by NIH grant AM-14881.

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Heckel, A., and K. M. Hasselbach. "PREDICTION OF THE THREE-DIMENSIONAL STRUCTURE OF THE ENZYMATIC PART OF T-PA." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644407.

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Up to now the three-dimensional structure of t-PA or parts of this enzyme is unknown. Using computer graphical methods the spatial structure of the enzymatic part of t-PA is predicted on the hypothesis, the three-dimensional backbone structure of t-PA being similar to that of other serine proteases. The t-PA model was built up in three steps:1) Alignment of the t-PA sequence with other serine proteases. Comparison of enzyme structures available from Brookhaven Protein Data Bank proved elastase as a basis for modeling.2) Exchange of amino acids of elastase differing from the t-PA sequence. The replacement of amino acids was performed such that backbone atoms overlapp completely and side chains superpose as far as possible.3) Modeling of insertions and deletions. To determine the spatial arrangement of insertions and deletions parts of related enzymes such as chymotrypsin or trypsin were used whenever possible. Otherwise additional amino acid sequences were folded to a B-turn at the surface of the proteine, where all insertions or deletions are located. Finally the side chain torsion angles of amino acids were optimised to prevent close contacts of neigh bouring atoms and to improve hydrogen bonds and salt bridges.The resulting model was used to explain binding of arginine 560 of plasminogen to the active site of t-PA. Arginine 560 interacts with Asp 189, Gly 19 3, Ser 19 5 and Ser 214 of t-PA (chymotrypsin numbering). Furthermore interaction of chromo-genic substrate S 2288 with the active site of t-PA was studied. The need for D-configuration of the hydrophobic amino acid at the N-terminus of this tripeptide derivative could be easily explained.

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Marcus, A. J., L. B. Safier, H. L. Ullman, N. Islam, M. J. Broekman, and C. V. Schacky. "NEW EICOSANOIDS FORMED DURING PLATELET-NEUTROPHIL INTERACTIONS." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644626.

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In physiologic and pathologic processes such as hemostasis, thrombosis and inflammation, multiple cell types are brought into close proximity - thereby increasing the possibility of metabolic interactions in the microenvironment. Activated platelets synthesize12-hydroxyeicosatetraenoic acid (12-HETE) in the presence or absence of aspirin. During a cell-cell interaction, platelet 12-HETE is metabolized by a cytochrome P-450 enzyme system in unstimulated neutrophils to 12.20-dihydroxyeicosatetraenoic acid (12,20-DiHETE). Recently, we observed time-dependent formation of a new eicosanoid following exposure of neutrophils to 12-HETE. This compound is more polar than the parent eicosanoid 12,20-DiHETE (reversed-phase HPLC). Incubation of purified 12,20-DiHETE with neutrophils resulted in a progressive decrease in the 12,20-DiHETE with increasing formation of the polar metabolite. In the absence of neutrophils, 12.20-DiHETE was quantitatively unchanged. The new metabolite of 12.20-DiHETE has been tentatively identified as 12-hydroxyeicosatetraen-l,20-dioic acid. The UV absorption maximum of the new compound is 237 nm which is identical to that of 12-HETE and 12,20-DiHETE. 20-hydroxy-LTB4 is the omega-hydroxylated derivative of the pro-inflammatory eicosanoid LTB4. When added to neutrophils 15 sec prior to 12,20-DiHETE, equimolar concentrations of 20-hydroxy-LTB4 (2.8uM) inhibited formation of the new metabolite by 28%. A concentration of 8uM 20-hydroxy-LTB4 inhibited the reaction by 49%. These results indicate that the neutrophil enzyme system responsible for conversion of 20-hydroxy-LTB4 to 20-carboxy-LTB4 may also be involved in further metabolism of-12,20-DiHETE. Neutrophil homogenization resulted in loss of the capacity to transform 12.20-DiHETE to the new metabolite despite pretreatment with DFP and addition of NADPH. Our data provide further evidence for the occurrence of transcellular metabolic events during thrombosis and the inflammatory response.

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Reports on the topic "Enzyme interaction"

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Freeman, Stanley, and Russell J. Rodriguez. The Interaction Between Nonpathogenic Mutants of Colletotrichum and Fusarium, and the Plant Host Defense System. United States Department of Agriculture, September 2000. http://dx.doi.org/10.32747/2000.7573069.bard.

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The intent of this proposal was to study the interaction between nonpathogenic mutants of Colletotrichum magna and Fusarium oxysporum, and the cucurbit host defense system. We had shown previously that a nonpathogenic endophytic mutant path- 1 of C. magna, caused no visible disease symptoms but protected watermelon seedlings from disease caused by the wildtype isolate and F. o. niveum. Objectives were: 1) Determine the microscopic, biochemical and molecular genetic interaction between "protected" (path- 1 colonized) cucurbit hosts and wildtype isolates of C. magna; 2) Isolate non-pathogenic mutants of F.o. melonis and test feasibility for protecting plants against fungal diseases. We found that path-1 caused no visible disease symptoms in cucurbit seedlings but conferred disease resistance against pathogenic isolates of C. magna, C. orbiculare, and F. oxysporum. Disease resistance conferred by path-1 correlated to a decrease in the time of activation of host defense systems after exposure of path-1 colonized plants to virulent pathogens. This was determined by monitoring the biochemical activity of PAL and peroxidase, and the deposition of lignin. It appears that path-1-conferred disease resistance is a multigenic phenomenon which should be more difficult for pathogen to overcome than single gene conferred resistance. Based on the benefits conferred by path-1, we have defined this mutant as expressing a mutualistic lifestyle. REMI (restriction enzyme-mediated integration) nonpathogenic mutants were also isolated using pHA1.3 plasmid linearized with Hind III and transformed into wildtype C. magna. The integrated vector and flanking genomic DNA sequences in REMI mutant R1 was re-isolated and cloned resulting in a product of approximately 11 kb designated pGMR1. Transformations of wildtype C. magna with pGMR1 resulted in the same non-pathogenic phenotype. A nonpathogenic mutant of F.o. melonis (pathogenic to melon) was isolated that colonized melon plants but elicited no disease symptoms in seedlings and conferred 25 - 50% disease protection against the virulent wildtype isolate. Subsequently, nonpathogenic mutant isolates of F.o. niveum (pathogenic to watermelon) were also isolated. Their protection capacity against the respective wildtype parent is currently under investigation. This research has provided information toward a better understanding of host-parasite interactions; specifically, endophytes, pathogens and their hosts. It will also allow us to assess the potential for utilizing nonpathogenic mutants as biological control agents against fungal pathogens and isolating molecular genetic factors of pathogenicity in Fusarium.

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Manulis, Shulamit, Christine D. Smart, Isaac Barash, Guido Sessa, and Harvey C. Hoch. Molecular Interactions of Clavibacter michiganensis subsp. michiganensis with Tomato. United States Department of Agriculture, January 2011. http://dx.doi.org/10.32747/2011.7697113.bard.

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Clavibacter michiganensis subsp. michiganensis (Cmm), the causal agent of bacterial wilt and canker of tomato, is the most destructive bacterial disease of tomato causing substantial economic losses in Israel, the U.S.A. and worldwide. The molecular strategies that allow Cmm, a Gram-positive bacterium, to develop a successful infection in tomato plants are largely unknown. The goal of the project was to elucidate the molecular interactions between Cmmand tomato. The first objective was to analyze gene expression profiles of susceptible tomato plants infected with pathogenic and endophytic Cmmstrains. Microarray analysis identified 122 genes that were differentially expressed during early stages of infection. Cmm activated typical basal defense responses in the host including induction of defense-related genes, production of scavenging of free oxygen radicals, enhanced protein turnover and hormone synthesis. Proteomic investigation of the Cmm-tomato interaction was performed with Multi-Dimensional Protein Identification Technology (MudPIT) and mass spectroscopy. A wide range of enzymes secreted by Cmm382, including cell-wall degrading enzymes and a large group of serine proteases from different families were identified in the xylem sap of infected tomato. Based on proteomic results, the expression pattern of selected bacterial virulence genes and plant defense genes were examined by qRT-PCR. Expression of the plasmid-borne cellulase (celA), serine protease (pat-1) and serine proteases residing on the chp/tomA pathogenicity island (chpCandppaA), were significantly induced within 96 hr after inoculation. Transcription of chromosomal genes involved in cell wall degradation (i.e., pelA1, celB, xysA and xysB) was also induced in early infection stages. The second objective was to identify by VIGS technology host genes affecting Cmm multiplication and appearance of disease symptoms in plant. VIGS screening showed that out of 160 tomato genes, which could be involved in defense-related signaling, suppression of 14 genes led to increase host susceptibility. Noteworthy are the genes Snakin-2 (inhibitor of Cmm growth) and extensin-like protein (ELP) involved in cell wall fortification. To further test the significance of Snakin -2 and ELP in resistance towards Cmm, transgenic tomato plants over-expressing the two genes were generated. These plants showed partial resistance to Cmm resulting in a significant delay of the wilt symptoms and reduction in size of canker lesion compared to control. Furthermore, colonization of the transgenic plants was significantly lower. The third objective was to assess the involvement of ethylene (ET), jasmonate (JA) and salicylic acid (SA) in Cmm infection. Microarray and proteomic studies showed the induction of enzymes involved in ET and JA biosynthesis. Cmm promoted ET production 8 days after inoculation and SIACO, a key enzyme of ET biosynthesis, was upregulated. Inoculation of the tomato mutants Never ripe (Nr) impaired in ET perception and transgenic plants with reduced ET synthesis significantly delayed wilt symptoms as compared to the wild-type plants. The retarded wilting in Nr plants was shown to be a specific effect of ET insensitivity and was not due to altered expression of defense related genes, reduced bacterial population or decrease in ethylene biosynthesis . In contrast, infection of various tomato mutants impaired in JA biosynthesis (e.g., def1, acx1) and JA insensitive mutant (jai1) yielded unequivocal results. The fourth objective was to determine the role of cell wall degrading enzymes produced by Cmm in xylem colonization and symptoms development. A significance increase (2 to 7 fold) in expression of cellulases (CelA, CelB), pectate lyases (PelA1, PelA2), polygalacturonase and xylanases (XylA, XylB) was detected by qRT-PCR and by proteomic analysis of the xylem sap. However, with the exception of CelA, whose inactivation led to reduced wilt symptoms, inactivation of any of the other cell wall degrading enzymes did not lead to reduced virulence. Results achieved emphasized the complexity involved in Cmm-tomato interactions. Nevertheless they provide the basis for additional research which will unravel the mechanism of Cmm pathogenicity and formulating disease control measures.

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Schaffer, Arthur, Jack Preiss, Marina Petreikov, and Ilan Levin. Increasing Starch Accumulation via Genetic Modification of the ADP-glucose Pyrophosphorylase. United States Department of Agriculture, October 2009. http://dx.doi.org/10.32747/2009.7591740.bard.

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The overall objective of the research project was to utilize biochemical insights together with both classical and molecular genetic strategies to improve tomato starch accumulation. The proposal was based on the observation that the transient starch accumulation in the immature fruit serves as a reservoir for carbohydrate and soluble sugar content in the mature fruit, thereby impacting on fruit quality. The general objectives were to optimize AGPase function and activity in developing fruit in order to increase its transient starch levels. The specific research objectives were to: a) perform directed molecular evolution of the limiting enzyme of starch synthesis, AGPase, focussing on the interaction of its regulatory and catalytic subunits; b) determine the mode of action of the recently identified allelic variant for the regulatory subunit in tomato fruit that leads to increased AGPase activity and hence starch content. During the course of the research project major advances were made in understanding the interaction of the small and large subunits of AGPase, in particular the regulatory roles of the different large subunits, in determining starch synthesis. The research was performed using various experimental systems, including bacteria and Arabidopsis, potato and tomato, allowing for broad and meaningful conclusions to be drawn. A novel discovery was that one of the large subunits of tomato AGPase is functional as a monomer. A dozen publications describing the research were published in leading biochemical and horticultural journals. The research results clearly indicated that increasing AGPase activity temporally in the developing fruit increase the starch reservoir and, subsequently, the fruit sugar content. This was shown by a comparison of the carbohydrate balance in near-isogenic tomato lines differing in a gene encoding for the fruit-specific large subunit (LS1). The research also revealed that the increase in AGPase activity is due to a temporal extension of LS1 gene expression in the developing fruit which in turn stabilizes the limiting heterotetrameric enzyme, leading to sustained starch synthesis. This genetic variation can successfully be utilized in the breeding of high quality tomatoes.

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Watkins, Chris B., Susan Lurie, Amnon Lers, and Patricia L. Conklin. Involvement of Antioxidant Enzymes and Genes in the Resistance Mechanism to Postharvest Superficial Scald Development. United States Department of Agriculture, December 2004. http://dx.doi.org/10.32747/2004.7586539.bard.

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The objective of this research project was to evaluate the involvement of antioxidant enzymes and genes in the resistance mechanism to postharvest superficial scald development using two primary systems: 1. Resistant and susceptible progenies of an apple cross between a scald resistant crab apple, ‘White Angel’ and a scald susceptible cultivar, ‘Rome Beauty’; 2. Heat-treatment of ‘Granny Smith’, which is known to reduce scald development in this cultivar. In 2002 we asked for, and received (October 14), permission to revise our initial objectives. The US side decided to expand their results to include further work using commercial cultivars. Also, both sides wanted to include an emphasis on the interaction between these antioxidant enzymes and the á-farnesene pathway, with the cooperation of a third party, Dr. Bruce Whitaker, USDA-ARS, Beltsville. Background: Superficial scald is a physiological storage disorder that causes damage to the skin of apple and pear fruit. It is currently controlled by use of an antioxidant, diphenylamine (DPA), applied postharvest by drenching or dips, but concern exists about such chemical usage especially as it also involves application of fungicides. As a result, there has been increased emphasis on understanding of the underlying mechanisms involved in disorder development. Our approach was to focus on the oxidative processes that occur during scald development, and specifically on using the two model systems described above to determine if the levels of specific antioxidants and/or antioxidant enzyme activities correlated with the presence/absence of scald. It was hoped that information about the role of antioxidant-defense mechanisms would lead to identification of candidate genes for future transgenic manipulation. Major conclusions, solutions, achievements: Collectively, our results highlight the complexity of superficial scald developmental processes. Studies involving comparisons of antioxidant enzyme activities in different crab apple selection, commercial cultivars, and in response to postharvest heat and 1-methylcyclopropene (1-MCP) treatments, show no simple direct relationships with antioxidant contents and susceptibility of fruit to scald development. However, a correlative relationship was found between POX activity or isoenzyme number and scald resistance in most of the studies. This relationship, if confirmed, could be exploited in breeding for scald resistance. In addition, our investigations with key genes in the á-farnesenebiosynthetic pathway, together with antioxidant processes, are being followed up by analysis of exposed and shaded sides of fruit of cultivars that show different degrees of scald control by 1-MCP. These data may further reveal productive areas for future research that will lead to long term control of the disorder. However, given the complexity of scald development, the greatest research need is the production of transgenic fruit with down-regulated genes involved in á- farnesene biosynthesis in order to test the currently popular hypothesis for scald development.

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Danson, Michael J., and David W. Hough. Multi-Enzyme Complexes in the Thermophilic Archaea: The Effects of Temperature on Stability, Catalysis and Enzyme Interactions in a Multi-Component System. Fort Belvoir, VA: Defense Technical Information Center, January 2012. http://dx.doi.org/10.21236/ada567244.

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Horwitz, Benjamin, and Nicole M. Donofrio. Identifying unique and overlapping roles of reactive oxygen species in rice blast and Southern corn leaf blight. United States Department of Agriculture, January 2017. http://dx.doi.org/10.32747/2017.7604290.bard.

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Plants and their fungal pathogens both produce reactive oxygen species (ROS). CytotoxicROS act both as stressors and signals in the plant-fungal interaction. In biotrophs, a compatible interaction generates little ROS, but is followed by disease. An incompatible interaction results in a strong oxidative burst by the host, limiting infection. Necrotrophs, in contrast, thrive on dead and dying cells in an oxidant-rich local environment. Rice blast, Magnaportheoryzae, a hemibiotroph, occurs worldwide on rice and related hosts and can decimate enough rice each year to feed sixty million people. Cochliobolusheterostrophus, a necrotroph, causes Southern corn leaf blight (SLB), responsible for a major epidemic in the 1970s. The objectives of our study of ROS signaling and response in these two cereal pathogens were: Confocal imaging of ROS production using genetically encoded redox sensor in two pathosystems over time. Forward genetic screening of HyPer sensor lines in two pathosystems for fungal genes involved in altered ROSphenotypes. RNA-seq for discovery of genes involved in ROS-related stress and signaling in two pathosystems. Revisions to the research plan: Library construction in SLB was limited by low transformation efficiency, compounded by a protoplasting enzyme being unavailable during most of year 3. Thus Objective 2 for SLB re-focused to construction of sensor lines carrying deletion mutations in known or candidate genes involved in ROS response. Imaging on rice proved extremely challenging, so mutant screening and imaging were done with a barley-infecting line, already from the first year. In this project, ROS imaging at unprecedented time and spatial resolution was achieved, using genetically-encoded ratio sensors in both pathogens. This technology is currently in use for a large library of rice blast mutants in the ROS sensor background, and Southern corn leaf blight mutants in final stages of construction. The imaging methods developed here to follow the redox state of plant pathogens in the host tissue should be applicable to fungal pathogens in general. Upon completion of mutant construction for SCLB we hope to achieve our goal of comparison between intracellular ROS status and response in hemibiotroph and necrotroph cereal pathogens.

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7

Steffens, John C., and Eithan Harel. Polyphenol Oxidases- Expression, Assembly and Function. United States Department of Agriculture, January 1995. http://dx.doi.org/10.32747/1995.7571358.bard.

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Polyphenol oxidases (PPOs) participate in the preparation of many plant products on the one hand and cause considerable losses during processing of plant products on the other hand. However, the physiological functions of plant PPO were still a subject of controversy at the onset of the project. Preliminary observations that suggested involvement of PPOs in resistance to herbivores and pathogens held great promise for application in agriculture but required elucidation of PPO's function if modulation of PPO expression is to be considered for improving plant protection or storage and processing of plant products. Suggestions on a possible role of PPO in various aspects of chloroplast metabolism were also relevant in this context. The characterization of plant PPO genes opened a way for achieving these goals. We reasoned that "understanding PPO targeting and routing, designing ways to manipulate its expression and assessing the effects of such modifications will enable determination of the true properties of the enzyme and open the way for controlling its activity". The objective of the project was to "obtain an insight into the function and biological significance of PPOs" by examining possible function(s) of PPO in photosynthesis and plant-pest interactions using transgenic tomato plants; extending our understanding of PPO routing and assembly and the mechanism of its thylakoid translocation; preparing recombinant PPOs for use in import studies, determination of the genuine properties of PPOs and understanding its assembly and determining the effect of PPO's absence on chloroplast performance. Results obtained during work on the project made it necessary to abandon some minor objectives and devote the effort to more promising topics. Such changes are mentioned in the 'Body of the report' which is arranged according to the objectives of the original proposal. The complex expression pattern of tomato PPO gene family was determined. Individual members of the family are differentially expressed in various parts of the plant and subjected to developmentally regulated turnover. Some members are differentially regulated also by pathogens, wounding and chemical wound signals. Wounding systemically induces PPO activity and level in potato. Only tissues that are developmentally competent to express PPO are capable of responding to the systemic wounding signal by increased accumulation of PPO mRNA. Down regulation of PPO genes causes hyper susceptibility to leaf pathogens in tomato while over expression regulation of PPO expression in tomato plants is their apparent increased tolerance to drought. Both the enhanced disease resistance conferred by PPO over expression and the increased stress tolerance due to down regulation can be used in the engineering of improved crop plants. Photosynthesis rate and variable fluorescence measurements in wild type, and PPO-null and over expressing transgenic tomato lines suggest that PPO does not enable plants to cope better with stressful high light intensities or reactive oxygen species. Rather high levels of the enzyme aggravate the damage caused under such conditions. Our work suggests that PPO's primary role is in defending plants against pathogens and herbivores. Jasmonate and ethylene, and apparently also salicylate, signals involved in responses to wounding and defense against herbivores and pathogens, enhance markedly and specifically the competence of chloroplasts to import and process pPPO. The interaction of the precursor with thylakoid membranes is primarily affected. The routing of PPO shows other unusual properties: stromal processing occurs in two sites, resulting in intermediates that are translocated across thylakoids by two different mechanisms - a DpH- and a Sec-dependent one. It is suggested that the dual pattern of processing and routing constitutes a'fail safe' mechanism, reflecting the need for a rapid and flexible response to defense challenges. Many of the observations described above should be taken into consideration when manipulation of PPO expression is contemplated for use in crop improvement.

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8

Christopher, David A., and Avihai Danon. Plant Adaptation to Light Stress: Genetic Regulatory Mechanisms. United States Department of Agriculture, May 2004. http://dx.doi.org/10.32747/2004.7586534.bard.

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Original Objectives: 1. Purify and biochemically characterize RB60 orthologs in higher plant chloroplasts; 2. Clone the gene(s) encoding plant RB60 orthologs and determine their structure and expression; 3. Manipulate the expression of RB60; 4. Assay the effects of altered RB60 expression on thylakoid biogenesis and photosynthetic function in plants exposed to different light conditions. In addition, we also examined the gene structure and expression of RB60 orthologs in the non-vascular plant, Physcomitrella patens and cloned the poly(A)-binding protein orthologue (43 kDa RB47-like protein). This protein is believed to a partner that interacts with RB60 to bind to the psbA5' UTR. Thus, to obtain a comprehensive view of RB60 function requires analysis of its biochemical partners such as RB43. Background & Achievements: High levels of sunlight reduce photosynthesis in plants by damaging the photo system II reaction center (PSII) subunits, such as D1 (encoded by the chloroplast tpsbAgene). When the rate of D1 synthesis is less than the rate of photo damage, photo inhibition occurs and plant growth is decreased. Plants use light-activated translation and enhanced psbAmRNA stability to maintain D1 synthesis and replace the photo damaged 01. Despite the importance to photosynthetic capacity, these mechanisms are poorly understood in plants. One intriguing model derived from the algal chloroplast system, Chlamydomonas, implicates the role of three proteins (RB60, RB47, RB38) that bind to the psbAmRNA 5' untranslated leader (5' UTR) in the light to activate translation or enhance mRNA stability. RB60 is the key enzyme, protein D1sulfide isomerase (Pill), that regulates the psbA-RN :Binding proteins (RB's) by way of light-mediated redox potentials generated by the photosystems. However, proteins with these functions have not been described from higher plants. We provided compelling evidence for the existence of RB60, RB47 and RB38 orthologs in the vascular plant, Arabidopsis. Using gel mobility shift, Rnase protection and UV-crosslinking assays, we have shown that a dithiol redox mechanism which resembles a Pill (RB60) activity regulates the interaction of 43- and 30-kDa proteins with a thermolabile stem-loop in the 5' UTR of the psbAmRNA from Arabidopsis. We discovered, in Arabidopsis, the PD1 gene family consists of II members that differ in polypeptide length from 361 to 566 amino acids, presence of signal peptides, KDEL motifs, and the number and positions of thioredoxin domains. PD1's catalyze the reversible formation an disomerization of disulfide bonds necessary for the proper folding, assembly, activity, and secretion of numerous enzymes and structural proteins. PD1's have also evolved novel cellular redox functions, as single enzymes and as subunits of protein complexes in organelles. We provide evidence that at least one Pill is localized to the chloroplast. We have used PDI-specific polyclonal and monoclonal antisera to characterize the PD1 (55 kDa) in the chloroplast that is unevenly distributed between the stroma and pellet (containing membranes, DNA, polysomes, starch), being three-fold more abundant in the pellet phase. PD1-55 levels increase with light intensity and it assembles into a high molecular weight complex of ~230 kDa as determined on native blue gels. In vitro translation of all 11 different Pill's followed by microsomal membrane processing reactions were used to differentiate among PD1's localized in the endoplasmic reticulum or other organelles. These results will provide.1e insights into redox regulatory mechanisms involved in adaptation of the photosynthetic apparatus to light stress. Elucidating the genetic mechanisms and factors regulating chloroplast photosynthetic genes is important for developing strategies to improve photosynthetic efficiency, crop productivity and adaptation to high light environments.

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Birk, Yehudit, Karl J. Kramer, Shalom W. Applebaum, and G. R. Reeck. Structure and Function of Protease Inhibitors from Legume Seeds and Cereal Grains and their Interaction with Digestive Enzymes of Stored Product Insects. United States Department of Agriculture, September 1986. http://dx.doi.org/10.32747/1986.7566729.bard.

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Steffens, John, Eithan Harel, and Alfred Mayer. Coding, Expression, Targeting, Import and Processing of Distinct Polyphenoloxidases in Tissues of Higher Plants. United States Department of Agriculture, November 1994. http://dx.doi.org/10.32747/1994.7613008.bard.

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Polyphenol oxidase (PPO) catalyzes the oxidation of phenols to quinones at the expense of O2. PPOs are ubiquitous in higer plants, and their role in oxidative browning of plant tissues causes large annual losses to food production. Despite the importance of PPOs to agriculture, the function(s) of PPOs in higher plants are not understood. Among other roles, PPOs have been proposed to participate in aspects of chloroplast metabolism, based on their occurrence in plastids and high Km for O2. Due to the ability of PPO to catalyze formation of highly reactive quinones, PPOs have also been proposed to be involved in a wide array of defensive interactions with insect, bacterial, and fungal pests. Physiological and biochemical studies of PPO have provided few answers to the major problems of PPO function, subcellular localization, and biochemical properties. This proposal achieved the following major objectives: cloning of PPO cDNAs in potato and tomato; characterization of the tomato PPO gene family; antisense downregulation of the tomato PPO gene family; and reduction in post-harvest enzymic browning of potato through expression of antisense PPO genes under the control of tuber-specific promoters. In addition, we established the lumenal localization of PPO, characterized and clarified the means by which PPOs are imported and processed by chloroplasts, and provided insight into the factors which control localization of PPOs. This proposal has thereby provided fundamental advances in the understanding of this enzyme and the control of its expression.

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