Literatura académica sobre el tema "Proline residues"
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Artículos de revistas sobre el tema "Proline residues"
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McDONNELL, MAEVE, RICHARD FITZGERALD, IDE NI FHAOLÁIN, P. VINCENT JENNINGS y GERARD O'CUINN. "Purification and characterization of aminopeptidase P from Lactococcus lactis subsp. cremoris". Journal of Dairy Research 64, n.º 3 (agosto de 1997): 399–407. http://dx.doi.org/10.1017/s0022029997002318.
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Aminopeptidase P was purified 65·3-fold from the cytoplasm of Lactococcus lactis subsp. cremoris AM2 with a 5·8% yield. The purified enzyme was found to consist of one polypeptide chain with a relative molecular mass of 41600. Metal chelating agents were found to be inhibitory and Mn2+ and Co2+ stimulated activity 7-fold and 6-fold respectively. The purified enzyme removed the N-terminal amino acid from peptides only where proline (and in one case alanine) was present in the penultimate position. No hydrolysis was observed either with dipeptides even when proline was present in the C-terminal position or when either N-terminal proline or pyroglutamate was present preceding a proline residue in the penultimate position of longer peptides. On the basis of this substrate specificity either aminopeptidase P or post-proline dipeptidyl aminopeptidase are necessary along with a broad specificity aminopeptidase to effect complete hydrolysis of casein-derived peptides containing a single internally placed proline residue. However, both aminopeptidase P and post-proline dipeptidyl aminopeptidase would be required together with a broad specificity aminopeptidase in order to completely hydrolyse casein-derived peptides that contain two internally placed consecutive proline residues. As bitter casein-derived peptides are likely to contain either single prolines or pairs of prolines, aminopeptidase P appears to be an important enzyme for debittering.
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Nishimura, Akira, Yurie Takasaki, Shota Isogai, Yoichi Toyokawa, Ryoya Tanahashi y Hiroshi Takagi. "Role of Gln79 in Feedback Inhibition of the Yeast γ-Glutamyl Kinase by Proline". Microorganisms 9, n.º 9 (7 de septiembre de 2021): 1902. http://dx.doi.org/10.3390/microorganisms9091902.
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Awamori, the traditional distilled alcoholic beverage of Okinawa, Japan, is brewed with the yeast Saccharomyces cerevisiae. During the distillation process after the fermentation, enormous quantities of distillation residues containing yeast cells must be disposed of, and this has recently been recognized as a major problem both environmentally and economically. Proline, a multifunctional amino acid, has the highest water retention capacity among amino acids. Therefore, distillation residues with large amounts of proline could be useful in cosmetics. Here, we isolated a yeast mutant with high levels of intracellular proline and found a missense mutation (Gln79His) on the PRO1 gene encoding the γ-glutamyl kinase Pro1, a limiting enzyme in proline biosynthesis. The amino acid change of Gln79 to His in Pro1 resulted in desensitization to the proline-mediated feedback inhibition of GK activity, leading to the accumulation of proline in cells. Biochemical and in silico analyses showed that the amino acid residue at position 79 is involved in the stabilization of the proline binding pocket in Pro1 via a hydrogen-bonding network, which plays an important role in feedback inhibition. Our current study, therefore, proposed a possible mechanism underlying the feedback inhibition of γ-glutamyl kinase activity. This mechanism can be applied to construct proline-accumulating yeast strains to effectively utilize distillation residues.
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Belova, Elena, Oksana Maksimenko, Pavel Georgiev y Artem Bonchuk. "The Essential Role of Prolines and Their Conformation in Allosteric Regulation of Kaiso Zinc Finger DNA-Binding Activity by the Adjacent C-Terminal Loop". International Journal of Molecular Sciences 23, n.º 24 (7 de diciembre de 2022): 15494. http://dx.doi.org/10.3390/ijms232415494.
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Kaiso is a methyl-DNA-binding protein containing three C2H2 zinc fingers with a C-terminal extension that participates in DNA binding. The linker between the last zinc finger and the DNA-binding portion of the extension contains two prolines that are highly conserved in vertebrates and in cognate ZBTB4 and ZBTB38 proteins. Prolines provide chain rigidity and can exist in cis and trans conformations that can be switched by proline isomerases, affecting protein function. We found that substitution of the conserved proline P588, but not of P577, to alanine, negatively affected KaisoDNA-binding according to molecular dynamics simulation and in vitro DNA-binding assays. Molecular dynamics simulations of the Kaiso DNA-binding domain with P588 either substituted to alanine or switched to the cis-conformation revealed similar alterations in the H-bonding network and uncovered allosteric effects leading to structural rearrangements in the entire domain that resulted in the weakening of DNA-binding affinity. The substitution of proline with a large hydrophobic residue led to the same negative effects despite its ability to partially rescue the intrinsic DNA-binding activity of the C-terminal loop. Thus, the presence of the C-terminal extension and cis-conformation of proline residues are essential for efficient Kaiso–DNA binding, which likely involves intramolecular tension squeezing the DNA chain.
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Deber, Charles M., Barbara J. Sorrell y Guang-Yi Xu. "Conformation of proline residues in bacteriorhodopsin". Biochemical and Biophysical Research Communications 172, n.º 2 (octubre de 1990): 862–69. http://dx.doi.org/10.1016/0006-291x(90)90755-c.
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SHELDEN, Megan C., Patrick LOUGHLIN, M. Louise TIERNEY y Susan M. HOWITT. "Proline residues in two tightly coupled helices of the sulphate transporter, SHST1, are important for sulphate transport". Biochemical Journal 356, n.º 2 (24 de mayo de 2001): 589–94. http://dx.doi.org/10.1042/bj3560589.
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The sulphate transporter SHST1, from Stylosanthes hamata, features three tightly coupled transmembrane helices which include proline residues that are conserved in most related transporters. We used site-directed mutagenesis and expression of the mutant transporters in yeast to test whether these proline residues are important for function. Four proline residues were replaced by both alanine and leucine. Only one of these proline residues, Pro-144, was essential for sulphate transport. However, mutation of either Pro-133 or Pro-160 resulted in a severe decrease in sulphate transport activity; this was due more to a decrease in transport activity than to a decrease in the amount of mutant SHST1 in the plasma membrane. These results suggest that all three proline residues are important for transport, and that the conformation of the three tightly coupled helices may play a critical role in sulphate transport. We also show that SHST1 undergoes a post-translational modification that is required for trafficking to the plasma membrane.
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Nakajima, Yoshitaka, Kiyoshi Ito, Makoto Sakata, Yue Xu, Kanako Nakashima, Futoshi Matsubara, Susumi Hatakeyama y Tadashi Yoshimoto. "Unusual Extra Space at the Active Site and High Activity for Acetylated Hydroxyproline of Prolyl Aminopeptidase from Serratia marcescens". Journal of Bacteriology 188, n.º 4 (15 de febrero de 2006): 1599–606. http://dx.doi.org/10.1128/jb.188.4.1599-1606.2006.
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ABSTRACT The prolyl aminopeptidase complexes of Ala-TBODA [2-alanyl-5-tert-butyl-(1, 3, 4)-oxadiazole] and Sar-TBODA [2-sarcosyl-5-tert-butyl-(1, 3, 4)-oxadiazole] were analyzed by X-ray crystallography at 2.4 Å resolution. Frames of alanine and sarcosine residues were well superimposed on each other in the pyrrolidine ring of proline residue, suggesting that Ala and Sar are recognized as parts of this ring of proline residue by the presence of a hydrophobic proline pocket at the active site. Interestingly, there was an unusual extra space at the bottom of the hydrophobic pocket where proline residue is fixed in the prolyl aminopeptidase. Moreover, 4-acetyloxyproline-βNA (4-acetyloxyproline β-naphthylamide) was a better substrate than Pro-βNA. Computer docking simulation well supports the idea that the 4-acetyloxyl group of the substrate fitted into that space. Alanine scanning mutagenesis of Phe139, Tyr149, Tyr150, Phe236, and Cys271, consisting of the hydrophobic pocket, revealed that all of these five residues are involved significantly in the formation of the hydrophobic proline pocket for the substrate. Tyr149 and Cys271 may be important for the extra space and may orient the acetyl derivative of hydroxyproline to a preferable position for hydrolysis. These findings imply that the efficient degradation of collagen fragment may be achieved through an acetylation process by the bacteria.
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Homareda, Haruo, Kiyoshi Kawakami, Kei Nagano y Hideo Matsui. "Stabilization in microsomal membranes of the fifth transmembrane segment of the Na+,K+-ATPase α subunit with proline to leucine mutation". Biochemistry and Cell Biology 71, n.º 7-8 (1 de julio de 1993): 410–15. http://dx.doi.org/10.1139/o93-060.
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We have reported that the fifth transmembrane segment of the Na+,K+-ATPase α subunit could not be inserted into microsomal membranes when it was synthesized from the truncated α1 cDNA. In this study, three proline residues in the segment were changed into leucine residues by site-directed mutagenesis. Replacement of all three proline residues by leucine residues allowed the insertion of this segment and its translocation. This result confirms our previous finding and demonstrates that three proline residues in the fifth transmembrane segment prevent insertion of the segment into the membrane.Key words: Na+,K+-ATPase, transmembrane segment, membrane insertion, site-directed mutagenesis.
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Delos, S. E., J. M. Gilbert y J. M. White. "The Central Proline of an Internal Viral Fusion Peptide Serves Two Important Roles". Journal of Virology 74, n.º 4 (15 de febrero de 2000): 1686–93. http://dx.doi.org/10.1128/jvi.74.4.1686-1693.2000.
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ABSTRACT The fusion peptide of the avian sarcoma/leukosis virus (ASLV) envelope protein (Env) is internal, near the N terminus of its transmembrane (TM) subunit. As for most internal viral fusion peptides, there is a proline near the center of this sequence. Robson-Garnier structure predictions of the ASLV fusion peptide and immediate surrounding sequences indicate a region of order (β-sheet), a tight reverse turn containing the proline, and a second region of order (α-helix). Similar motifs (order, turn or loop, order) are predicted for other internal fusion peptides. In this study, we made and analyzed 12 Env proteins with substitutions for the central proline of the fusion peptide. Env proteins were expressed in 293T cells and in murine leukemia virus pseudotyped virions. We found the following. (i) All mutant Envs form trimers, but when the bulky hydrophobic residues phenylalanine or leucine are substituted for proline, trimerization is weakened. (ii) Surprisingly, the proline is required for maximal processing of the Env precursor into its surface and TM subunits; the amount of processing correlates linearly with the propensity of the substituted residue to be found in a reverse turn. (iii) Nonetheless, proteolytically processed forms of all Envs are preferentially incorporated into pseudotyped virions. (iv) All Envs bind receptor with affinity greater than or equal to wild-type affinity. (v) Residues that support high infectivity cluster with proline at intermediate hydrophobicity. Infectivity is not supported by mutant Envs in which charged residues are substituted for proline, nor is it supported by the trimerization-defective phenylalanine and leucine mutants. Our findings suggest that the central proline in the ASLV fusion peptide is important for the formation of the native (metastable) Env structure as well as for membrane interactions that lead to fusion.
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Doerfel, Lili K., Ingo Wohlgemuth, Christina Kothe, Frank Peske, Henning Urlaub y Marina V. Rodnina. "EF-P Is Essential for Rapid Synthesis of Proteins Containing Consecutive Proline Residues". Science 339, n.º 6115 (13 de diciembre de 2012): 85–88. http://dx.doi.org/10.1126/science.1229017.
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Elongation factor P (EF-P) is a translation factor of unknown function that has been implicated in a great variety of cellular processes. Here, we show that EF-P prevents ribosome from stalling during synthesis of proteins containing consecutive prolines, such as PPG, PPP, or longer proline strings, in natural and engineered model proteins. EF-P promotes peptide-bond formation and stabilizes the peptidyl–transfer RNA in the catalytic center of the ribosome. EF-P is posttranslationally modified by a hydroxylated β-lysine attached to a lysine residue. The modification enhances the catalytic proficiency of the factor mainly by increasing its affinity to the ribosome. We propose that EF-P and its eukaryotic homolog, eIF5A, are essential for the synthesis of a subset of proteins containing proline stretches in all cells.
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Heidenreich, Steffi, Pamela Weber, Heike Stephanowitz, Konstantin M. Petricek, Till Schütte, Moritz Oster, Antti M. Salo et al. "The glucose-sensing transcription factor ChREBP is targeted by proline hydroxylation". Journal of Biological Chemistry 295, n.º 50 (6 de octubre de 2020): 17158–68. http://dx.doi.org/10.1074/jbc.ra120.014402.
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Cellular energy demands are met by uptake and metabolism of nutrients like glucose. The principal transcriptional regulator for adapting glycolytic flux and downstream pathways like de novo lipogenesis to glucose availability in many cell types is carbohydrate response element–binding protein (ChREBP). ChREBP is activated by glucose metabolites and post-translational modifications, inducing nuclear accumulation and regulation of target genes. Here we report that ChREBP is modified by proline hydroxylation at several residues. Proline hydroxylation targets both ectopically expressed ChREBP in cells and endogenous ChREBP in mouse liver. Functionally, we found that specific hydroxylated prolines were dispensable for protein stability but required for the adequate activation of ChREBP upon exposure to high glucose. Accordingly, ChREBP target gene expression was rescued by re-expressing WT but not ChREBP that lacks hydroxylated prolines in ChREBP-deleted hepatocytes. Thus, proline hydroxylation of ChREBP is a novel post-translational modification that may allow for therapeutic interference in metabolic diseases.
Tesis sobre el tema "Proline residues"
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Marotta, Nicole. "Mycoplasma pneumoniae protein P30 proline residues: Cytadherence, gliding motility, and P30 stability". Miami University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=miami1412010755.
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Gaddie, Keith J. "Structural Elements that Regulate Interactions between the Extracellular and Transmembrane Domains of Human Nucleoside Triphosphate Diphosphohydrolase 3". University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1259077311.
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TEDESCHI, GIULIA. "Effect of electrostatic charges on aggregation and conformation of intrinsically disordered proteins". Doctoral thesis, Università degli Studi di Milano-Bicocca, 2018. http://hdl.handle.net/10281/198946.
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Intrinsecamente disordinata” viene definita una proteina nativa priva di struttura secondaria o terziaria, non esposta ad agenti denaturanti. Le proteine con queste caratteristiche sono indicate come IDP/IDR, e rappresentano una ampia porzione del proteoma di tutti gli esseri viventi. Le IDP sono coinvolte in molte funzioni fisiologiche e patologiche, come la formazione di organuli cellulari privi di membrane e nei processi di fibrillazione associate ad amiloidosi. Entrambi questi fenomeni appaiono sempre più associati alla capacità delle IDP di formare interazioni intermolecolari. Stati patologici possono essere causati da disfunzioni e cattiva regolazione delle proprietà conformazionali e di aggregazione delle IDP. L’aggregazione e la conformazione delle IDP sono state ascritte a diversi fattori: la lunghezza della sequenza, le interazioni idrofobiche, i legami ad idrogeno e le cariche elettrostatiche. A questa ultima abbiamo rivolto la nostra attenzione dal momento che le IDP sono ricche di amminoacidi carichi. La carica netta per residuo (NCPR), la frazione totale di residui carichi (FCR) e la distribuzione di residui di carica opposta (valore κ) sono stati considerati i principali determinanti della dimensione della catena e delle classi conformazionali delle IDP. La prima parte del piano sperimentale interessa il concetto di NCPR, cioè la carica netta normalizzata per la lunghezza della proteina. Il nostro obiettivo è di descrivere come questo parametro influenzi la risposta delle IDP a cambiamenti di pH, con conseguente perdita di solubilità. Come modello viene utilizzata PNT del virus del morbillo ed a partire da questa si ottiene un array di varianti aventi la stessa idrofobicità e FCR, ma differenti per NCPR ed il punto isoelettrico (pI). Le proteine analizzate mostrano solubilità minima in corrispondenza del loro valore di pI, come atteso, ma tale diminuzione di solubilità non è uniforme, ma guidata dal valore di NCPR di ciascuna variante proteica. I nostri dati suggeriscono che la solubilità complessiva della proteina sia legata al valore di NCPR. La seconda parte del lavoro si è ispirata al concetto di clusterizzazione di cariche ed ha come obiettivo la valutazione di come le proprietà di compattezza delle IDP dipendano dal valore di κ. In questo caso sono state utilizzate due IDP ben caratterizzate, NTAIL dal virus del morbillo e PNT4 da Hendra virus. Grazie alla possibilità di modificare la sequenza amminoacidica delle IDP, senza interferire sul complessivo disordine strutturale, entrambi i geni sono stati riprogettati. Sono stati ottenuti due set di proteine sintetiche, ciascuno contenente una proteina wt e due varianti in cui le cariche sono uniformemente distribuite (low κ) o completamente segregate all’N- ed al C-terminus (high κ). Le proprietà conformazionali della proteina wt e delle corrispondenti varianti sono valutate mediante tecniche biofisiche. Complessivamente i dati sperimentali confermano il trend atteso cioè un aumento del grado di compattezza conformazionale all’aumentare dei valori di κ, secondo una proporzione che è tipica di ciascuna proteina in relazione al suo contenuto di proline. Complessivamente i nostri risultati confermano precedenti dati computazionali e sperimentali suggerendo come residui carichi, attraverso la loro frequenza (NCPR) e la distribuzione (κ) influenzino solubilità e compattezza delle IDP. I due lavori sperimentali sottolineano il contesto, ambientale (ad esempio le condizioni di pH) o di sequenza (la % di proline), in cui NCPR e distribuzione di cariche sono più efficaci nel determinare le caratteristiche di solubilità e compattezza conformazionale delle IDP. La rilevanza di queste informazioni è legata non solo allo studio IDP naturali, ma anche alla progettazione razionale di proteine non naturali con proprietà aggregative e conformazionali ben definite“Intrinsic disorder” is generally referred to the conformational status of native proteins lacking of secondary and/or tertiary structure, although not exposed to any denaturing agent. These proteins, which are called intrinsically disordered (IDP/IDRs) represent a large class in the proteomes of all living beings, with a remarkable abundance among more complex eukaryotes and viruses. IDPs have been recognized to be involved in many relevant physiological and pathological functions, such as the coacervation of membrane-less organelles or the fibrillation in amyloid bodies. It is becoming clearer that fast and massive intermolecular interactions involving IDPs are governing both kinds of phenomena and that pathologies can arise from dysregulations of conformational properties and aggregation ability. The conformation and aggregation features of IDPs have been ascribed in turn to several factors, such as sequence length, hydrophobic interactions, hydrogen bonds or electrostatic charges. The latter deserve particular attention since charged residues are particularly abundant in IDPs. The net charge per residue (NCPR), the total fraction of charged residues (FCR), and the linear distribution of opposite charges (κ value) have been recently regarded as the primary determinants of IDPs conformational properties. The first part of the experimental work presented in this thesis was inspired by the concept of NCPR, which represents the net charge normalized by the protein length. The aim is to describe how the NCPR influences the ability of IDPs to respond to environment pH changes through loss of solubility. PNT from measles virus was used as a model IDP. Moreover, the wild type (wt) protein was compared with an array of PNT variants sharing the same hydrophobicity and total number of charged residues (FCR), but differing in net charges per residue and isoelectric points (pI). Tested proteins showed a solubility minimum close to their pI, as expected, but the pH-dependent decrease of solubility was not uniform and driven by the NCPR of each variant. Our data suggest that the overall solubility of a protein can be dictated by protein regions endowed with NCPR and, hence, prompter to respond to pH changes. The second part of experimental work was inspired by the concept of charge clustering. The aim was consisting at verifying that the compaction properties of IDPs are tunable by the κ value. We have used two well-characterized IDPs, namely measles virus NTAIL and Hendra virus PNT4, as model systems. Taking advantage of the high sequence designability of IDPs, genes of PNT4 and NTAIL were redesigned to obtain two sets of synthetic proteins each including the wild type (wt) form and two “κ variants”. In low-κ variants, charged amino acids are most evenly distributed, in high-κ variants charges are clustered as much as possible at the N- and C-termini (high κ). κ variants, along with wt forms, were subjected to various biophysical techniques to assess their conformational properties.Overall, experimental data confirm the expected trend, with compactness increasing with κ value. The increase of compactness does not follow a general trend, but it is protein-specific and related to the proline content. All together, these findings confirm previous theoretical and experimental data on the role of charged residues frequency (NCPR) and distribution (κ). The main value of this experimental work is in pinpointing the context, which is the environment – pH – or the amino acid composition – proline % –, where such driving forces of aggregation and compaction are mostly effective. This knowledge is useful not only to describe how the conformational behavior of IDPs is encoded by their amino acid sequence, but also to rationally design non-natural IDPs with desired conformational and aggregation properties
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Huang, Yi-Ting y 黃怡婷. "Design Disulfied-Bond and Proline residues to Improve the Thermostability of Streptomyces clavuligerus Deacetoxycephalosporin C Synthase". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/32269018420687567736.
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Lin, Ni-Shine. "Molecular Structure of Proline Containing Amyloid Fibrils Formed by Residues 127 to 147 of the Human Prion Protein". 2008. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-1707200800383100.
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Murrali, Maria Grazia. "Characterization of intrinsically disordered proteins by nuclear magnetic resonance spectroscopy". Doctoral thesis, 2019. http://hdl.handle.net/2158/1179640.
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During my doctorate, I focused my studies on the development of NMR methods for the characterization of IDPs and on their application to study challenging cases. The combination of 13C detection with new hardware tools such as Multiple Receivers, and new software tools such as Automated Projection, led to new strategies to speed up NMR experiments. Moreover, modification of base pulse sequences led to simple 13C NMR experiments for the characterization of proline residues, that are highly abundant in IDPs and less straightforward to be investigated with standard HN-based NMR experiments. Together with the development of new methods, I worked on their application to study different aspects of IDPs function.NMR spectroscopy was used for the characterization of a large viral disordered protein, and the study of an unexpected liquid-liquid phase transition likely relevant in the biological mechanism of viral infection. Exploiting NMR we were able to study the interaction between a disordered protein involved in Parkinson’s disease and a small molecule that can be a potential drug to contrast the pathology, as well as the interaction between an oncogenic viral protein and the disordered region of a transcriptional coactivator. These interesting applications demonstrate once again the importance of NMR spectroscopy for studying IDPs, adding small but important pieces in the knowledge about the role of protein disorder in biology.
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Grewal, Natasha. "Fragmentation reactions of oligopeptides containing a proline residue /". 2004.
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Thesis (M.Sc.)--York University, 2004. Graduate Programme in Chemistry.Typescript. Includes bibliographical references. Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: LINK NOT YET AVAILABLE.
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"The role of proline residue to the thermostability of proteins". 2005. http://library.cuhk.edu.hk/record=b5896424.
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Ma Hoi-Wah.Thesis (M.Phil.)--Chinese University of Hong Kong, 2005.
Includes bibliographical references (leaves 113-120).
Abstracts in English and Chinese.
Acknowledgement --- p.I
Abstract --- p.II
摘要 --- p.III
Content --- p.IV
Abbreviations --- p.X
List of Figures --- p.XII
List of Tables --- p.XIV
Chapter Chapter One --- Introduction --- p.1
Chapter 1.1 --- Interactions that stabilize proteins --- p.1
Chapter 1.2 --- Some common strategies of protein engineering to improve thermostability --- p.6
Chapter 1.3 --- Ribosomal protein T. celer L30e as a study model for thermostability --- p.7
Chapter 1.4 --- Extra proline residue is one of the insights by comparing the two proteins --- p.10
Chapter Chapter Two --- Materials and Methods --- p.13
Chapter 2.1 --- General Techniques --- p.13
Chapter 2.1.1 --- Preparation of Escherichia coli competent cells --- p.13
Chapter 2.1.2 --- Transformation of Escherichia coli competent cells --- p.14
Chapter 2.1.3 --- Spectrophotometric quantitation of DNA --- p.14
Chapter 2.1.4 --- Agarose gel electrophoresis --- p.14
Chapter 2.1.5 --- DNA extraction from agarose gel electrophoresis using Viogene Gene Clean kit --- p.15
Chapter 2.1.6 --- Plasmid DNA minipreperation by Wizard® Plus SV Minipreps DNA Purification System from Promega --- p.16
Chapter 2.1.7 --- Polymerase Chain Reaction (PCR) --- p.17
Chapter 2.1.8 --- Ligation of DNA fragments --- p.18
Chapter 2.1.9 --- Sonication of pellet resuspension --- p.18
Chapter 2.1.10 --- SDS-polyacrylamide gel electrophoresis (SDS-PAGE) --- p.19
Chapter 2.1.11 --- Native polyacrylamide gel electrophoresis --- p.20
Chapter 2.1.12 --- Staining of protein in polyacrylamide gel by Coommassie Brillant Blue R250 --- p.22
Chapter 2.1.13 --- Protein Concentration determination --- p.22
Chapter 2.2 --- Cloning the Mutant Genes --- p.22
Chapter 2.2.1 --- Site-directed mutagenesis --- p.22
Chapter 2.2.1.1 --- Generation of full length mutant gene by megaprimer --- p.23
Chapter 2.2.1.2 --- Generation of mutant gene by QuikChange® Site-Directed Mutagenesis Kit from Stratagene --- p.26
Chapter 2.2.2 --- Restriction Digestion of DNA --- p.27
Chapter 2.2.3 --- Ligation of DNA fragments --- p.27
Chapter 2.2.4 --- Screening for successful inserted plasmid clones from ligation reactions --- p.28
Chapter 2.2.4.1 --- By PCR --- p.28
Chapter 2.2.4.2 --- By restriction digestion --- p.28
Chapter 2.2.5 --- DNA sequencing --- p.29
Chapter 2.3 --- Expression and Purification of Protein --- p.29
Chapter 2.3.1 --- "General bacterial culture, harvesting and lysis" --- p.29
Chapter 2.3.2 --- Purification of recombinant wild type TRP and mutants --- p.30
Chapter 2.3.3 --- Purification of recombinant wild type YRP and mutants --- p.32
Chapter 2.4 --- Thermodynamic Studies by Circular Dichroism (CD) Spectrometry --- p.34
Chapter 2.4.1 --- Thermodynamic studies by guanidine-induced denaturations --- p.34
Chapter 2.4.2 --- Themodynamic studies by thermal denaturations --- p.36
Chapter 2.4.3 --- ACp measurement of the TRP mutants --- p.37
Chapter 2.4.3.1 --- By Gibbs-Helmholtz analysis --- p.37
Chapter 2.4.3.2 --- By van't Hoff analysis --- p.37
Chapter 2.5 --- Crystal Screen for the Mutant T. celer L30e --- p.38
Chapter 2.5.1 --- T. celer L30e Pro→Ala and Pro→Gly mutants --- p.38
Chapter 2.5.2 --- Yeast L30e K65P mutant --- p.38
Chapter 2.6 --- Sequences of Primers --- p.39
Chapter 2.6.1 --- Primers for TRP and its mutants --- p.39
Chapter 2.6.2 --- Primers for YRP and its mutantsReagents and buffers --- p.40
Chapter 2.7 --- Reagents and Buffers --- p.40
Chapter 2.7.1 --- Reagents for competent cell preparation --- p.40
Chapter 2.7.2 --- Nucleic acid eletrophoresis buffers --- p.41
Chapter 2.7.3 --- Media for bacterial culture --- p.41
Chapter 2.7.4 --- Reagents for SDS-PAGE --- p.42
Chapter 2.7.5 --- Buffers for TRP purification --- p.44
Chapter 2.7.6 --- Buffers for YRP purification --- p.45
Chapter 2.7.7 --- Buffer for Circular Dichroism (CD) Spectrometry --- p.46
Chapter Chapter Three --- Results --- p.48
Chapter 3.1 --- "Cloning, expression and purification of the mutant proteins" --- p.48
Chapter 3.1.1 --- "Mutagenesis, cloning and purification of the thermophilic proteins - T. celer L30e protein and its mutants" --- p.48
Chapter 3.1.2 --- "Mutagenesis, cloning and purification of the mesophilic proteins - yeast L30e protein and its mutants" --- p.52
Chapter 3.2 --- Stability of Pro→Ala/Gly mutants of T. celer L30e at 298K --- p.55
Chapter 3.2.1 --- Design of alanine and glycine mutants from thermophilic homologue --- p.55
Chapter 3.2.2 --- "Among alanine mutants, only P59A was destabilized" --- p.55
Chapter 3.2.3 --- Ala→Gly mutations destabilized the protein --- p.59
Chapter 3.3 --- Stability of Xaa→Pro mutants of yeast L30e at 298K --- p.61
Chapter 3.3.1 --- Design of proline mutants from mesophilic homologue --- p.61
Chapter 3.3.2 --- "K65P, corresponding to P59 in T. celer L30e, stabilized yeast L30e" --- p.62
Chapter 3.3.3 --- Yeast L30e mutated with thermophilic consensus sequence did not give a more stable protein --- p.65
Chapter 3.4 --- Temperature dependency of the stability of the mutants of T. celer L30e --- p.67
Chapter 3.4.1 --- The trend of ΔGU was consistence through 25 to 75°C --- p.67
Chapter 3.4.2 --- Melting temperatures of T. celer mutants determined by thermal denaturations --- p.68
Chapter 3.5 --- pH dependency of melting temperatures --- p.75
Chapter 3.5.1 --- ΔCP values of the P59A/G mutants determined by van't HofF's analyses increased significantly --- p.77
Chapter 3.6 --- No structural change was observed in the crystal structure of P59A --- p.80
Chapter Chapter Four --- Discussion --- p.84
Chapter 4.1 --- The trend of stability from guanidine-induced denaturation agreed with that from thermal denaturations --- p.86
Chapter 4.2 --- The magnitude of destabilization of P59A and Ala→Gly mutation was consistent with the expected destabilization due to entropy --- p.87
Chapter 4.3 --- Entropic effect had little effect for residues in flexible region --- p.93
Chapter 4.4 --- Stabilization forces that compensate the entropic effect --- p.96
Chapter 4.5 --- Compensatory stabilization due to the release of amide group --- p.99
Chapter 4.5.1 --- Intra-molecular H-bond in P88A --- p.99
Chapter 4.5.2 --- Solvent-protein H-bond in P43A --- p.103
Chapter 4.6 --- Consensus concept was not applicable in our model --- p.110
Chapter 4.7 --- "Pro→Ala mutation destabilized the protein increase the protein's ACP value, however enthalpy and entropy change were difficult to be decomposed" --- p.111
Chapter 4.8 --- Concluding Remarks --- p.112
References --- p.113
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邱玲瑩. "Effects of Substituting a Proline Residue on the Structure and the Cu(II) Affinity of Prion Protein Fragments". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/84276381889117778379.
Texto completoLibros sobre el tema "Proline residues"
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Sorrell, Barbara Jane. Conformation of proline residues in bacteriorhodopsin. Ottawa: National Library of Canada, 1990.
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Saarloos, Wim y José Dijck. The Dutch Polder Model in science and research. NL Amsterdam: Amsterdam University Press, 2017. http://dx.doi.org/10.5117/9789462988163.
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Scientific research in the Netherlands is doing remarkably well. Dutch researchers, universities and institutes reside at or near the top of international rankings. In this essay, José van Dijck and Wim van Saarloos, the president and vice-president of the Royal Netherlands Academy of Arts and Sciences (KNAW), explore how such a small country could become a global player in science and research. They highlight interconnectedness, collaboration, trust, and interwoven research and education among the quintessentially Dutch factors that paved the way to the success. They also show, however, that the country's efforts to reach the top sometimes chip away at these trusted foundations. Investments in its research base are lagging, and some typically Dutch strengths have recently come under pressure. They close off with some suggestions on how the country may turn the tide, prolong its great achievements, and ensure a leading role for Dutch research in the nation's future.
Capítulos de libros sobre el tema "Proline residues"
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Deber, Charles M., Guang-Yi Xu y Barbara J. Sorrell. "Proline residues in bacteriorhodopsin: Conformation and temperature dependence". En Proteins, 82–86. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-010-9063-6_12.
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Kitakuni, Eiichi, Yasushi Oda y Toshiki Tanaka. "Design of α-helical coiled coil peptide containing periodic proline residues". En Peptides, 378–80. Dordrecht: Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-011-2264-1_140.
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Ruzza, Paolo, Chiara Rubini, Giuliano Siligardi, Rohanah Hussain, Andrea Calderan, Andrea Guiotto, Luca Cesaro, Anna M. Brunati y Arianna Donella-Deana. "Introduction of N-alkyl Residues in Proline-rich Peptides: Effect on SH3 Binding Affinity and Peptide Conformation". En Advances in Experimental Medicine and Biology, 65–66. New York, NY: Springer New York, 2009. http://dx.doi.org/10.1007/978-0-387-73657-0_28.
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Breznik, Matej, Simona Golič Grdadolnik, Gerald Giester, Ivan Leban y Danijel Kikelj. "Influence of Stereochemistry of the Preceding Acyl Residue on the cis/trans Ratio of the Proline Peptide Bond". En Peptides: The Wave of the Future, 330–31. Dordrecht: Springer Netherlands, 2001. http://dx.doi.org/10.1007/978-94-010-0464-0_151.
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Shi, Gaotao, Jia Zeng, Chunfeng Liu y Keqiu Li. "Minimize Residual Energy of the 3-D Underwater Sensor Networks with Non-uniform Node Distribution to Prolong the Network Lifetime". En Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, 647–59. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-030-00916-8_59.
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Hinck, A. P. y W. F. Walkenhorst. "NMR and Mutagenesis Investigations of a Model Cis: Trans Peptide tsomerization Reaction: Xaa116-Pro117of Staphylococcal Nuclease and its Role in Protein Stability and Folding". En Biological NMR Spectroscopy. Oxford University Press, 1997. http://dx.doi.org/10.1093/oso/9780195094688.003.0016.
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The slow rates of peptide bond isomerization in imino acids and the substantial population of the cis peptide bond isomer in Xaa-Pro linkages in peptides were first recognized in NMR studies of proline-containing model compounds (Maia et al., 1971). The important role of this isomerization in protein stability and folding (reviewed by Kim and Baldwin, 1982, 1990; Schmid, 1993) were recognized several years later (Brandts et al., 1975) and the biological relevance of this process was substantiated by the discovery of a ubiquitous enzyme that catalyzes Xaa-Pro peptide bond isomerization (Fischer et al., 1984, 1989; Takahashi et al., 1989). The strict evolutionary conservation of some prolyl residues and the observation that the kinetics of interconversion between alternative functional forms of some systems is consistent with the time scale of proline isomerization suggest that proline isomerization may play a wide role in protein structure and function. Suggestive examples include the sodium pump of Escherichia coli, the disulfide isomerase/thioredoxin class of enzymes, concanavalin A, and bovine prothrornbin fragment I (Brown et al., 1977; Marsh et al, 1979; Dunker, 1982; Brandland Deber, 1986; Langsetmo et al, 1989). NMR spectroscopy is one of the most suitable tools for studying this isomerization reaction. The rates generally are slow on the time scale of NMR chemical shifts but, in favorable cases, are comparable to longitudinal relaxation rates so that the isomerization process can be investigated by chemical exchange spectroscopy. NMR data obtained on calbindin D9k (Chazin et al., 1989), insulin (Higgins et al., 1988), and staphylococcal nuclease (nuclease) as discussed below have shown that each exists in solution under native conditions as a mixture of slowly exchanging conformers. The fact that dynamic molecular heterogeneity in nuclease was first observed in the laboratory of Oleg Jardetzky, as manifested by splitting of the histidyl 1H ε1 resonance from His46 in one-dimensional 1H NMR spectra recorded at 100 MHz (Markley et al., 1970), makes this topic particularly appropriate to a volume celebrating his scientific contributions.
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Taber, Douglass F. "C-N Ring Construction: The Zakarian Synthesis of (-)-Rhazinilam". En Organic Synthesis. Oxford University Press, 2013. http://dx.doi.org/10.1093/oso/9780199965724.003.0055.
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William D. Wulff of Michigan State University developed (J. Am. Chem. Soc. 2010, 132, 13100; Org. Lett. 2010, 12, 4908) a general enantio- and diastereocontrolled route from an imine 1 to the aziridine 3. Craig W. Lindsley of Vanderbilt University established (Org. Lett. 2010, 12, 3276) a complementary approach (not illustrated). Joseph P. Konopelski of the University of California, Santa Cruz, designed (J. Am. Chem. Soc. 2010, 132, 11379) a practical and inexpensive flow apparatus for the cyclization of 4 to the β-lactam 5. Manas K. Ghorai of the Indian Institute of Technology, Kanpur, showed (J. Org. Chem. 2010, 75, 6173) that an aziridine 6 could be opened with malonate to give the γ-lactam 8. John P. Wolfe of the University of Michigan devised (J. Am. Chem. Soc. 2010, 132, 12157) a Pd catalyst for the enantioselective cyclization of 9 to 11. Sherry R. Chemler of the State University of New York at Buffalo observed (Angew. Chem. Int. Ed. 2010, 49, 6365) that the cyclization of 12 to 14 proceeded with high diastereoselectivity. Glenn M. Sammis of the University of British Columbia devised (Synlett 2010, 3035) conditions for the radical cyclization of 15 to 16. Jeffrey S. Johnson of the University of North Carolina observed (J. Am. Chem. Soc. 2010, 132, 9688) that the opening of racemic 17 with 18 could be effected with high ee. The residual 17 was highly enriched in the nonreactive enantiomer. Kevin D. Moeller of Washington University found (Org. Lett . 2010, 12, 5174) that the n -BuLi catalyzed cyclization of 20 set the quaternary center of 21 with high relative control. Yujiro Hayashi of the Tokyo University of Science, using the diphenyl prolinol TMS ether that he developed as an organocatalyst, designed (Org. Lett. 2010, 12, 4588) the sequential four-component coupling of 22, 23, benzaldehyde imine, and allyl silane to give 24 with high relative and absolute stereocontrol. Derrick L. J. Clive of the University of Alberta showed (J. Org. Chem. 2010, 75, 5223) that 25, prepared in enantiomerically pure form from serine, participated smoothly in the Claisen rearrangement, to deliver 27.
Actas de conferencias sobre el tema "Proline residues"
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Redzuan, Rohaiza Ahmad, Nor Muhammad Mahadi, Abdul Munir Abdul Murad, Shazilah Kamaruddin y Farah Diba Abu Bakar. "Targeted selection of amino acid residues to create variant libraries of Glaciozyma antarctica proline iminopeptidase". En THE 2018 UKM FST POSTGRADUATE COLLOQUIUM: Proceedings of the Universiti Kebangsaan Malaysia, Faculty of Science and Technology 2018 Postgraduate Colloquium. AIP Publishing, 2019. http://dx.doi.org/10.1063/1.5111243.
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Mayne, Leland C., Gregory P. Harhay y Bruce Hudson. "Applications of ultraviolet resonance Raman spectroscopy to protein structure". En International Laser Science Conference. Washington, D.C.: Optica Publishing Group, 1986. http://dx.doi.org/10.1364/ils.1986.thl59.
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Resonance Raman spectroscopy of heme proteins and the visual pigments has provided valuable insights into the mechanism of action of these proteins. The performance of Raman experiments with ultraviolet radiation permits resonance with nonchromophoric components of proteins including the peptide bond itself.1,2 Fluorescence from the aromatic residues of proteins does not obscure the Raman signal because the fluorescence occurs at longer wavelengths. The peptide bond gives rise to new Raman active bands with ultraviolet excitation.2 The imino linkage of X-proline sequences results in absorption in the 220–240-nm range where normal amino linkages are transparent. This permits the selective excitation of this group relative to the predominant amino peptide bonds. This is of particular interest with respect to the involvement of isomerization of the X-proline linkage in protein folding. Recent results using radiation in the 150–200-nm region are presented.
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Hanauske-Abel, Hartmut M., Bernadette M. Cracchiolo, Sukhwinder Singh y Axel-Rainer Hanauske. "Abstract 2030: Oncological relevance of protein hydroxylase inhibitors (PHI): results of testing an emerging concept with an orally active pioneer medicine that blocks the hydroxylations of proline and lysine residues". En Proceedings: AACR Annual Meeting 2021; April 10-15, 2021 and May 17-21, 2021; Philadelphia, PA. American Association for Cancer Research, 2021. http://dx.doi.org/10.1158/1538-7445.am2021-2030.
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Sampaio-Dias, Ivo, Beatriz L. Pires-Lima, Sara Silva-Reis, Xavier Cruz Correia, Hugo Costa-Almeida, Xerardo García-Mera y José Rodriguéz-Borges. "Exploring the bioisosterism of proline residue in melanostatin neuropeptide using heteroaromatic scaffolds". En 7th International Electronic Conference on Medicinal Chemistry. Basel, Switzerland: MDPI, 2021. http://dx.doi.org/10.3390/ecmc2021-11496.
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Saito, Koji, Takumi Kobayashi, Chika Sugimoto y Ryuji Kohno. "Routing algorithm considering nodes residual power to prolong ad-hoc network lifetime". En 2017 20th International Symposium on Wireless Personal Multimedia Communications (WPMC). IEEE, 2017. http://dx.doi.org/10.1109/wpmc.2017.8301848.
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Hunicz, Jacek y Maciej Mikulski. "Application of Variable Valve Actuation Strategies and Direct Gasoline Injection Schemes to Reduce Combustion Harshness and Emissions of Boosted HCCI Engine". En ASME 2018 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/icef2018-9625.
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One of the pending issues regarding Homogeneous Charge Compression Ignition (HCCI) engines is high load operation limit constrained by excessive pressure rise rates (PRRs). The present study investigates various measures to reduce combustion harness in a residual-affected HCCI engine. At the same time, the impact of those measures on efficiency and emissions is assessed. Experimental research was performed on a single cylinder engine equipped with a fully-flexible valvetrain mechanism and direct gasoline injection. The HCCI combustion mode with exhaust gas trapping was realized using negative valve overlap and fuel reforming, achieved via the injection of a portion of fuel during exhaust re-compression. Three measures are investigated for the PRR control under the same reference operating conditions, namely: (i) variable intake and exhaust valve timing, (ii) boost pressure adjustment and (iii) split fuel injection to control the amount of fuel injected for reforming. Variable exhaust valve timing enabled control of the amount of trapped residuals, and thus of the compression temperature. The reduction in the amount of trapped residuals, at elevated engine load, delays auto-ignition, which results in a simultaneous reduction of pressure rise rates and nitrogen oxides emissions. The effects of intake valve timing are much more complex, because they include the variability in the amount of intake air, the thermodynamic compression ratio as well as the in-cylinder fluid flow. It was found, however, that both early and late intake valve openings delay auto-ignition and prolong combustion. Additionally, the reduction of the amount of fuel injected during exhaust re-compression further delays combustion and reduces combustion rates. Intake pressure reduction has by far the largest effect on peak pressure reduction yet is connected with excessive NOx emissions. The research successfully identifies air-path and injection techniques, which allow for the control of combustion rates and emissions under elevated load regime, thus shorting the gap towards the real-world application of HCCI concepts.
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Sato, Kenji. "Amelioration of high fat diet-induced obesity in rat by short chain pyroglutamyl peptides in Japanese salted fermented soy paste (miso)". En 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/rowd7909.
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Japanese salted fermented soybean paste (miso) is used as seasonings for traditional Japanese dishes. These products still play important roles in the modern dietary habits of Japanese, while consumption of these products has decreased approximately to 30-50% of consumption since 1975. Miso is produced by a fungi (Aspergillus oryzae) starter, referred to koji. A. oryzae produces a strong protease including both endoproteinases and exopeptidases. Thus, these products contain short chain peptides in addition to free amino acids. However, little was known of their structure and biological functions due to difficulty in isolation. In the present study, pyroglutamyl peptides present in miso were identified by a liquid chromatography-tandem mass spectrometry (LC-MS/MS), detecting precursor ions, which generated immonium ion of pyroglutamyl residue (m/z 84). By using this method, 13 pyroglutamyl peptides were identified in four types of miso. Administration of the water extract prepared from 0.6 g soybean miso/kg body weight/day significantly suppressed high fat diet-induced obesity. A similar effect was exerted by the hydrophobic pyroglutamyl peptide fraction, including pyroglutamyl proline (pEP), pEV, pEI, and pEL. Administration of a mixture of synthetic pEP, pEV, pEI, and pEL in a ratio to that in miso or pEL alone also suppressed the weight gain in a dose dependent manner. It has been demonstrated that high fat diet-induced small intestinal dysbiosis plays critical role in inducing obesity. pEL has been demonstrated to attenuate high fat diet-induced dysbiosis via enhancing secretion of host antimicrobial peptide into lumen. These results suggest that the short-chain hydrophobic pyroglutamyl peptides present in miso are effective in suppressing high fat diet-induced obesity via normalizing dysbiosis.
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Su, Donghua, Zaoyuan Li, Xuning Wu, Jin Li, Jinfei Sun y Guanyi Zheng. "Cement Sheath Integrity Evaluation Under Multiple Cyclic Loading Using Mechanical Equivalent Experiment for Gas Storage Wells in Eastern China". En ASME 2022 41st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/omae2022-80440.
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Abstract Gas storage wells in eastern China have been in operation for nearly 30 years. Fatigue damage may have occurred in the cement sheath after years of injection-production cycles. If the risk of integrity failure of the cement sheath can be predicted accurately, optimization or remedial measures can be implemented over time to further prolong the life of gas storage wells. In this paper, we established a mechanical equivalent method to restore the wellbore load borne by the cement sheath to the self-developed wellbore simulation device, and carried out the cyclic load tests of 376, 141 and 54 rounds at the injection-production differential pressure of 5, 10 and 15 MPa, respectively. Based on this method and the twin-shear unified strength theory, the integrity failure mechanism of the cement sheath was analyzed. We found that after cyclic loading, the tensile strength of the cement sheath decreased. Fatigue-tensile failure was the main reason for the integrity failure of the cement sheath in gas storage wells. Residual tensile strength decreased with the increase in cycle time and injection-production differential pressure. Taking a gas storage well in eastern China as an example, it was found that if the well maintains the current injection-production differential pressure, there is a risk of cement sheath failure. In this regard, the optimization measures of reducing injection-production pressure difference were proposed to prolong wellbore life. At the same time, the suggestion of using a modified cement system in gas storage wells was also proposed. The research results can provide an important reference for predicting gas storage well life and designing mechanical properties of cement sheath.
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Enright, Michael P., R. Craig McClung, Kwai S. Chan, John McFarland, Jonathan P. Moody y James C. Sobotka. "Micromechanics-Based Fracture Risk Assessment Using Integrated Probabilistic Damage Tolerance Analysis and Manufacturing Process Models". En ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-58089.
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Materials engineering and damage tolerance assessment have traditionally been performed as disjoint processes involving repeated tests that can ultimately prolong the time required for certification of new materials. Computational advances have been made both in the prediction of material properties and probabilistic damage tolerance analysis, but have been pursued primarily as independent efforts. Integrated computational materials engineering (ICME) has the potential to significantly reduce the time required for development and insertion of new materials in the gas turbine industry. A manufacturing process software tool called DEFORM™ has been linked with a probabilistic damage tolerance analysis (PDTA) software tool called DARWIN® to form a new capability for ICME of gas turbine engine components. DEFORM simulates rotor manufacturing processes including forging, heat treating, and machining to compute residual stress and strain, track anomaly location, and predict microstructure including grain size and orientation. DARWIN integrates finite element stress analysis results, fracture mechanics models, material anomaly data, probability of anomaly detection, and inspection schedules to compute the probability of fracture of a gas turbine engine rotor as a function of operating cycles. Previous papers have focused on probabilistic modeling of residual stresses in DARWIN based on manufacturing process training data from DEFORM. This paper describes recent efforts to extend the probabilistic link between DEFORM and DARWIN to enable modeling of residual strain, average grain size, and ALA (unrecrystalized) grain size as random variables. Gaussian Process modeling is used to estimate the relationship among model responses and material processing parameters. These random variables are applied to microstructure-based fatigue crack nucleation and growth models for use in probabilistic risk assessments. The integrated DARWIN-DEFORM capability is demonstrated for a representative engine disk model which illustrates the influences of manufacturing-induced random variables on component fracture risk. The results provide critical insight regarding the potential benefits of integrating probabilistic computational material processing models with probabilistic damage tolerance-based risk assessment.
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Prueter, Phillip E. y Brian Macejko. "Establishing Recommended Guidance for Local Post Weld Heat Treatment Configurations Based on Thermal-Mechanical Finite Element Analysis". En ASME 2016 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/pvp2016-63581.
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Post weld heat treatment (PWHT) is an effective way to minimize weld residual stresses in pressure vessels and piping equipment. PWHT is required for carbon steels above a Code-defined thickness threshold and other low-alloy steels to mitigate the propensity for crack initiation and ultimately, brittle fracture. Additionally, PWHT is often employed to mitigate stress corrosion cracking due to environmental conditions. Performing local PWHT following component repairs or alterations is often more practical and cost effective than heat treating an entire vessel or a large portion of the pressure boundary. In particular, spot or bulls eye configurations are often employed in industry to perform PWHT following local weld repairs to regions of the pressure boundary. Both the ASME Boiler and Pressure Vessel (B&PV) Code and the National Board Inspection Code (NBIC) permit the use of local PWHT around nozzles or other pressure boundary repairs or alterations. Additionally, Welding Research Council (WRC) Bulletin 452 [1] offers detailed guidance relating to local PWHT and compares some of the Code-based methodologies for implementing local PWHT on pressure retaining equipment. Specifically, local PWHT methodologies provided in design Codes: ASME Section VIII Division 1 [2] and Division 2 [3], ASME Section III Subsection NB [4], British Standard 5500 [5], Australian Standard 1210 [6], and repair Codes: American Petroleum Institute (API) 510 [7] and NBIC [8] are discussed and compared in this study. While spot PWHT may be appropriate in certain cases, if the soak, heating, and gradient control bands are not properly sized and positioned, it can lead to permanent vessel distortion or detrimental residual stresses that can increase the likelihood of in-service crack initiation and possible catastrophic failure due to unstable flaw propagation. It is essential to properly engineer local or spot PWHT configurations to ensure that distortion, cracking of adjacent welds, and severe residual stresses are avoided. In some cases, this may require advanced thermal-mechanical finite element analysis (FEA) to simulate the local PWHT process and to predict the ensuing residual stress state of the repaired area. This paper investigates several case studies of local PWHT configurations where advanced, three-dimensional FEA is used to simulate the thermal-mechanical response of the repaired region on a pressure vessel and to optimize the most ideal PWHT arrangement. Local plasticity and distortion are quantified using advanced non-linear elastic-plastic analysis. Commentary on the ASME and NBIC Code-specified local PWHT requirements is rendered based on the detailed non-linear FEA results, and recommended good practice for typical local PWHT configurations is provided. Advanced computational simulation techniques such as the ones employed in this investigation offer a means for analysts to ensure that local PWHT configurations implemented following equipment repairs will not lead to costly additional damage, such as distortion or cracking that can ultimately prolong equipment downtime.
Informes sobre el tema "Proline residues"
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Zilberstein, Aviah, Bo Liu y Einat Sadot. Studying the Involvement of the Linker Protein CWLP and its Homologue in Cytoskeleton-plasma Membrane-cell Wall Continuum and in Drought Tolerance. United States Department of Agriculture, junio de 2012. http://dx.doi.org/10.32747/2012.7593387.bard.
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The study has been focused on proline-rich proteins from the HyPRP family. Three proline-rich proteins have been characterized with the CWLP as the main objective. We showed that this unique protein is assembled in the plasma membrane (PM) and forms a continuum between the cell wall (CW) and cytosol via the PM. While spanning the PM, it is arranged in lipid rafts as CWLP-aquaporin complexes that recruit PP2A-β”, as a part of PP2A enzyme, close to the aquaporin moiety where it dephosphorylates two crucial Ser residues and induces closure of the aquaporin water channels. The closure of water channels renders cells more tolerant to plasmolysis and plants to dehydration. This unique effect was observed not only in Arabidopsis, but also in potato plants over expressing the CWLP, suggesting a possible usage in crop plants as a valve that reduces loss of water or/and elevates cold resistance. The CWLP is a member of the HyPRP protein family that all possess structurally similar 8CM domain, predicted to localize to PM lipid rafts. In this study, two additional highly homologous HyPRP proteins were also studied. The GPRP showed the same localization and it’s over expression increased tolerance to lack of water. However, the third one, PRP940, despite sharing high homology in the 8CM domain, is completely different and is assembled in parallel to cortical microtubules in the cell. Moreover, our data suggest that this protein is not involved in rendering plants resistant to lack of water. We suggest implying CWLP as a tool for better regulation of water maintenance in crop plants.