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1
Yashchuk, V. M., I. V. Lebedyeva e O. M. Navozenko. "Manifestations of triplet electronic excitations migration in π-electron containing polymers". Bulletin of Taras Shevchenko National University of Kyiv. Series: Physics and Mathematics, n. 1 (2019): 242–45. http://dx.doi.org/10.17721/1812-5409.2019/1.55.
Testo completoAbstract (sommario):
The results of spectral studies of polymers with aromatic side groups are considered and analyzed. In particular, the phosphorescence spectra of polyvinylcarbazole (PVCa) polyvinyl-7-benzocarbazole (PV7BK) polypropylcarbazole (PEPC) are presented and analyzed. The phosphorescence of these polymers has been shown to be related to the migration of triplet excitons in macromolecules. The phosphorescence of PVC is determined at 77by deep traps (oxides), at 4.2 -shallow traps (monomer units of PVCa). The spreading length of triplet excitons in PVCa macromolecules is 600 A – that corresponds to the average distances between adjacent traps in the macromolecule. There are no such traps in PV7BK macromolecules. The boundary conditions for triplet excitons in macromolecules of PV7BCa were used for evaluation the excitons spreading length. With this aim the dependence of phosphorescence spectra on molecular weihgt were studied The effect of changing of spectral positions of phosphorescence bands when exciton rich the end macromolecular cell was used. The average trip length of triplet excitons is approximately 1000 A. This distance is in fact limited by the probability of the meeting of triplet excitons in the macromolecule and their annihilation at a given excitation intensity.
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Bazunova, Marina, Valentina Chernova, Roman Lazdin, Angela Shurshina, Anna Bazunova, Mariya Elinson e Elena Kulish. "Cosolvents Impact on some Properties of the Solutions and the Films of Succinamide Chitosan". Chemistry & Chemical Technology 14, n. 4 (15 dicembre 2020): 481–86. http://dx.doi.org/10.23939/chcht14.04.481.
Testo completoAbstract (sommario):
The article deals with the method of the medical purpose materials creation with the controlled physico-chemical and mechanical deformation properties on the basis of water-soluble derivative of amino polysaccharide chitosan – succinamide chitosan. The essence of the method is the macromolecules aggregation processes regulation in the initial solutions by the injection of organic cosolvents – acetone and ethanol. It has been stated that in a mixed solvent succinamide chitosan molecules are not in the form of the isolated macromolecular balls but as the macromolecules interacting (aggregated) systems. It has been proved that the presence of cosolvents decreases the polymer macromolecule links capability to interact with an enzyme and increases physico-mechanical characteristics of the film materials.
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Sharp, Kim A. "Analysis of the size dependence of macromolecular crowding shows that smaller is better". Proceedings of the National Academy of Sciences 112, n. 26 (15 giugno 2015): 7990–95. http://dx.doi.org/10.1073/pnas.1505396112.
Testo completoAbstract (sommario):
The aqueous milieu inside cells contains as much as 30–40% dissolved protein and RNA by volume. This large concentration of macromolecules is expected to cause significant deviations from solution ideality. In vivo biochemical reaction rates and equilibria might differ significantly from those measured in the majority of in vitro experiments that are performed at much lower macromolecule concentrations. Consequently crowding, a nonspecific phenomenon believed to arise from the large excluded volume of these macromolecules, has been studied extensively by experimental and theoretical methods. However, the relevant theory has not been applied consistently. When the steric effects of macromolecular crowders and small molecules like water and ions are treated on an equal footing, the effect of the macromolecules is opposite to that commonly believed. Large molecules are less effective at crowding than water and ions. There is also a surprisingly weak dependence on crowder size. Molecules of medium size, ∼5 Å radius, have the same effect as much larger macromolecules like proteins and RNA. These results require a reassessment of observed high-concentration effects and of strategies to mimic in vivo conditions with in vitro experiments.
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Hudder, Alice, Lubov Nathanson e Murray P. Deutscher. "Organization of Mammalian Cytoplasm". Molecular and Cellular Biology 23, n. 24 (15 dicembre 2003): 9318–26. http://dx.doi.org/10.1128/mcb.23.24.9318-9326.2003.
Testo completoAbstract (sommario):
ABSTRACT Although the role of macromolecular interactions in cell function has attracted considerable attention, important questions about the organization of cells remain. To help clarify this situation, we used a simple protocol that measures macromolecule release after gentle permeabilization for the examination of the status of endogenous macromolecules. Treatment of Chinese hamster ovary cells with saponin under carefully controlled conditions allowed entry of molecules of at least 800 kDa; however, there were minimal effects on internal cellular architecture and protein synthesis remained at levels comparable to those seen with intact cells. Most importantly, total cellular protein and RNA were released from these cells extremely slowly. The release of actin-binding proteins and a variety of individual cytoplasmic proteins mirrored that of total protein, while marker proteins from subcellular compartments were not released. In contrast, glycolytic enzymes leaked rapidly, indicating that cells contain at least two distinct populations of cytoplasmic proteins. Addition of microfilament-disrupting agents led to rapid and extensive release of cytoplasmic macromolecules and a dramatic reduction in protein synthesis. These observations support the conclusion that mammalian cells behave as highly organized, macromolecular assemblies (dependent on the actin cytoskeleton) in which endogenous macromolecules normally are not free to diffuse over large distances.
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Li, Chao, Xiangxiang Zhang, Mingdong Dong e Xiaojun Han. "Progress on Crowding Effect in Cell-like Structures". Membranes 12, n. 6 (3 giugno 2022): 593. http://dx.doi.org/10.3390/membranes12060593.
Testo completoAbstract (sommario):
Several biological macromolecules, such as proteins, nucleic acids, and polysaccharides, occupy about 30% of the space in cells, resulting in a crowded macromolecule environment. The crowding effect within cells exerts an impact on the functions of biological components, the assembly behavior of biomacromolecules, and the thermodynamics and kinetics of metabolic reactions. Cell-like structures provide confined and independent compartments for studying the working mechanisms of cells, which can be used to study the physiological functions arising from the crowding effect of macromolecules in cells. This article mainly summarizes the progress of research on the macromolecular crowding effects in cell-like structures. It includes the effects of this crowding on actin assembly behavior, tubulin aggregation behavior, and gene expression. The challenges and future trends in this field are presented at the end of the paper.
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Mohapatra, Somesh, Joyce An e Rafael Gómez-Bombarelli. "Chemistry-informed macromolecule graph representation for similarity computation, unsupervised and supervised learning". Machine Learning: Science and Technology 3, n. 1 (21 febbraio 2022): 015028. http://dx.doi.org/10.1088/2632-2153/ac545e.
Testo completoAbstract (sommario):
Abstract The near-infinite chemical diversity of natural and artificial macromolecules arises from the vast range of possible component monomers, linkages, and polymers topologies. This enormous variety contributes to the ubiquity and indispensability of macromolecules but hinders the development of general machine learning methods with macromolecules as input. To address this, we developed a chemistry-informed graph representation of macromolecules that enables quantifying structural similarity, and interpretable supervised learning for macromolecules. Our work enables quantitative chemistry-informed decision-making and iterative design in the macromolecular chemical space.
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Mormann, W., e K. H. Hellwich. "Structure-based nomenclature for cyclic organic macromolecules (IUPAC Recommendations 2008)". Pure and Applied Chemistry 80, n. 2 (1 gennaio 2008): 201–32. http://dx.doi.org/10.1351/pac200880020201.
Testo completoAbstract (sommario):
A structure-based nomenclature system for monocyclic and polycyclic organic macromolecules is presented. Single-strand mono- and polycyclic macromolecules as well as spiro macrocyclic compounds are covered. However, rotaxanes and catenanes, which contain interlocked rings, and rings or ring systems formed by noncovalent bonds are excluded. Also, polypeptides and carbohydrate polymers are not included. The nomenclature of cyclic macromolecules is based on the existing nomenclature of regular and irregular macromolecules, which in turn is based on the nomenclature of organic chemistry also published by IUPAC. The procedure for naming a cyclic macromolecule consists of transforming it to an open-chain regular or irregular macromolecule in such a way that naming of units proceeds in descending order of seniority but otherwise follows the rules established for these types of macromolecules. For polycyclic macromolecules, the same principles are followed after the main ring, bridges, and branch units are identified and locants for branch units as well as bridges are assigned. The complete names are assembled by citing the component names and locants in the appropriate order according to the rules in this document. Wherever possible, examples for illustration of the naming procedure have been chosen from the literature.
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Wang, Yang, Yan Dai, Qiang Luo, Xiaoli Wei, Xueyang Xiao, Haonan Li, Jiani Hu, Qiyong Gong, Jianlin Wu e Kui Luo. "Tumor Environment-Responsive Degradable Branched Glycopolymer Magnetic Resonance Imaging Contrast Agent and Its Tumor-Targeted Imaging". Journal of Biomedical Nanotechnology 15, n. 7 (1 luglio 2019): 1384–400. http://dx.doi.org/10.1166/jbn.2019.2759.
Testo completoAbstract (sommario):
Branched macromolecules have been used as carriers for imaging probes and drug delivery systems because of their tunable molecular structures, as well as their regular nanoscale structures and dimensions. We designed and synthesized two tumor environment-responsive branched and gadolinium (Gd)-based glycopolymer conjugates and investigated their potency as highly effective and safe magnetic resonance imaging (MRI) contrast agents. These branched macromolecules were prepared by one-pot reversible addition fragmentation chain transfer (RAFT) polymerization and conjugating chemistry. A biodegradable GFLG oligopeptide was used to successfully link the branch-chains of the branched macromolecules, finally a conjugate of this branched macromolecule and DOTA-Gd (HB-pGAEMA-Gd) with a molecular weight (MW) of 124 kDa was produced. Meanwhile, to improve the ability of tumor-targeting, we conjugated a tumor-targeting cRGDyK cyclic peptide to the branched molecule to prepare a tumor-targeted branched macromoleculeDOTA-Gd conjugate (HB-pGAEMA-RGD-Gd) with a MW of 136 kDa. The prepared branched macromolecules had a nanoscale hydrodynamic particle size and could be degraded into lower MW fragments with the cathepsin B. The aqueous phase relaxation efficiency of HB-pGAEMA-RGD-Gd (12.3 mM–1s–1 and HB-pGAEMA-Gd (13.2 mM–1s–1 was four times higher than that of DTPA-Gd (2.9 mM–1s–1), a clinically used contrast agent. In comparison with DTPA-Gd, the branched macromolecular contrast agents significantly enhanced the MRI signal intensity at the tumor site in vivo, and the enhancement of MRI signal intensity was up to 6 times that of the DTPA-Gd owing to their high relaxation efficiencies and accumulation at the tumor site. In addition, in vitro and in vivo toxicity studies indicated that the degradable macromolecular contrast agents had no significant toxicity.
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Pramod Kumar Mishra. "Theoretical estimate of the probability for macromole formation". JOURNAL OF ADVANCED APPLIED SCIENTIFIC RESEARCH 2, n. 4 (15 dicembre 2021): 1–8. http://dx.doi.org/10.46947/joaasr242020103.
Testo completoAbstract (sommario):
We estimate the polymerization probability of a macromolecule, where the macromolecule is made of distinct monomers; and there are different values of the fugacity for the addition of the monomers in the chain to form an infinitely long linear macromolecule of distinct monomers. The lattice model of the random walk has been used to mimic the conformations of an ideal chain in two and three dimensions, and this ideal chain is the macromolecules of distinct monomers. It has been shown through analytical estimates that the flexible macromolecules may be easily formed than the stiff macromolecules for both two and three dimensional cases. In the case of stiff chain, the ratio of the critical value of monomer fugacity is nothing but the log-log ratio of the Boltzmann’s weight corresponding to the monomers affinity corresponding to its conjugate monomer pair; and it is due to a fact that the stiff chain has small value of the entropy.
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Pawlak, Andrzej, e Justyna Krajenta. "Entanglements of Macromolecules and Their Influence on Rheological and Mechanical Properties of Polymers". Molecules 29, n. 14 (20 luglio 2024): 3410. http://dx.doi.org/10.3390/molecules29143410.
Testo completoAbstract (sommario):
Flexible macromolecules easily become entangled with neighboring macromolecules. The resulting network determines many polymer properties, including rheological and mechanical properties. Therefore, a number of experimental and modeling studies were performed to describe the relationship between the degree of entanglement of macromolecules and polymer properties. The introduction presents general information about the entanglements of macromolecule chains, collected on the basis of studies of equilibrium entangled polymers. It is also shown how the density of entanglements can be reduced. The second chapter presents experiments and models leading to the description of the movement of a single macromolecule. The next part of the text discusses how the rheological properties change after partial disentangling of the polymer. The results on the influence of the degree of chain entanglement on mechanical properties are presented.
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Emancipator, S. N., C. S. Rao, A. Amore, R. Coppo e J. G. Nedrud. "Macromolecular properties that promote mesangial binding and mesangiopathic nephritis." Journal of the American Society of Nephrology 2, n. 10 (aprile 1992): S149. http://dx.doi.org/10.1681/asn.v210s149.
Testo completoAbstract (sommario):
The hydrodynamic size, electrostatic charge, and specificity are established determinants of the site of glomerular localization of macromolecules. Larger macromolecules or aggregates and anionic charge are associated with mesangial deposits, despite the fact that the mesangial matrix bears a negative charge similar to that of the capillary wall. Antigens such as Sendai virus, a model infectious pathogen, gliadin, a model dietary/environmental agent and fibronectin, a model endogenous macromolecule, bind to mesangial cells in vitro on the basis of cell surface glycoconjugates. Nonantibody immunoglobulin A, which does not bind to cells directly, binds to these elements via different carbohydrate specificities (simple sugar inhibition). Such binding promotes or augments macromolecular deposition in the mesangium. More significantly, mesangial deposits per se are not pathogenic, because normal renal function can be observed with florid deposits. Pathogenic deposits must have properties that alter mesangial cell metabolism or interaction with the matrix. Although complement activation is well recognized, complement-independent mechanisms related to cell surface modulation are being recognized. In vitro, antigen/immunoglobulin A aggregates alter mesangial cell eicosanoid synthesis. In vivo, large-lattice cross-linking by particulate antigen promotes hematuria. We conclude that the binding of macromolecules to cells and the cross-linking of cell surface molecules cause alterations in the mesangial cells and therefore in glomerular function. The mesangial cell, rather than a passive respondent, is an active participant in the genesis of glomerulonephritis.
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Mittal, Shruti, Rimpy Kaur Chowhan e Laishram Rajendrakumar Singh. "Macromolecular crowding: Macromolecules friend or foe". Biochimica et Biophysica Acta (BBA) - General Subjects 1850, n. 9 (settembre 2015): 1822–31. http://dx.doi.org/10.1016/j.bbagen.2015.05.002.
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Garner, M. M., e M. B. Burg. "Macromolecular crowding and confinement in cells exposed to hypertonicity". American Journal of Physiology-Cell Physiology 266, n. 4 (1 aprile 1994): C877—C892. http://dx.doi.org/10.1152/ajpcell.1994.266.4.c877.
Testo completoAbstract (sommario):
The nonideal properties of solutions containing high concentrations of macromolecules can result in enormous increases in the activity of the individual macromolecules. It has been proposed that molecular crowding and confinement occur in cells and are major determinants of the activity of the proteins and other intracellular macromolecules. This concept has important implications for cell volume regulation because, under crowded conditions, relatively small changes in concentration, consequent to alterations of water content, lead to large changes in macromolecular activity. This review considers several aspects of macromolecular crowding and confinement, including: 1) the physical chemical principles involved; 2) in vitro demonstrations of the effects; 3) relation to water activity; 4) estimates of the actual intracellular activity of water and macromolecules; 5) relation to osmotic regulation in various types of cells, including bacteria, red blood cells, and complex nucleated cells; and 6) the relation to inorganic ions and organic osmolytes in cells stressed by hypertonicity. We conclude that, while there is compelling evidence for important effects of molecular crowding in vitro and in red blood cells, the role of macromolecular crowding and confinement in osmotic regulation of more complex cells is an open question that deserves the extensive attention it is currently receiving.
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Prasetyanti, Intan Kris, Sukardiman Sukardiman e Suharjono Suharjono. "Molecular Docking of Mangostin and Sinensetin Derivatives on SUR1-Pancreatic KATP Channel Target as Antidiabetic". JURNAL FARMASI DAN ILMU KEFARMASIAN INDONESIA 8, n. 3 (30 novembre 2021): 271. http://dx.doi.org/10.20473/jfiki.v8i32021.271-276.
Testo completoAbstract (sommario):
Background: Diabetes Mellitus (DM) is a complex chronic disease characterized by increased blood glucose. The incidence of this disease is rising, especially type 2 diabetes which is caused by insulin resistance in the body. SUR1-Pancreatic KATP Channel is a receptor as an antidiabetic target because its inhibition process can increase insulin production so that it can reduce blood glucose in people with type 2 diabetes. Objective: This study aims to identify the in-silico activity of the SUR1-Pancreatic KATP Channel macromolecules. Methods: Identification of macromolecular binding sites using Protein Plus software, then carried out molecular docking using AutoDock software, where the formed molecular interactions are further identified using the BIOVIA Discovery Studio software. Results: After determining the macromolecular binding site, the RMSD value was 1.253, allowing for further molecular docking. Molecular docking showed that the Ligands of mangostin (α, β, γ-mangostin) and sinensetin derivatives had a good affinity, namely α-mangostin -6,31 kcal/mol; β-mangostin -5.78 kcal/mol; γ-mangostin -6.17 kcal/mol and sinensetin -4.75 kcal/mol. Conclusion: The affinity sequence in the docking process for the SUR1 KATP channel macromolecules is α-mangostin > γ-mangostin > β-mangostin > sinensetin. The highest affinity for the docking process on the macromolecule SUR1 KATP channel was α-mangostin with a value of ΔG -6.31 kcal/mol Ki 23.65 μM.
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Chen, Kuo, e Murugappan Muthukumar. "Entropic barrier of topologically immobilized DNA in hydrogels". Proceedings of the National Academy of Sciences 118, n. 28 (6 luglio 2021): e2106380118. http://dx.doi.org/10.1073/pnas.2106380118.
Testo completoAbstract (sommario):
The single most intrinsic property of nonrigid polymer chains is their ability to adopt enormous numbers of chain conformations, resulting in huge conformational entropy. When such macromolecules move in media with restrictive spatial constraints, their trajectories are subjected to reductions in their conformational entropy. The corresponding free energy landscapes are interrupted by entropic barriers separating consecutive spatial domains which function as entropic traps where macromolecules can adopt their conformations more favorably. Movement of macromolecules by negotiating a sequence of entropic barriers is a common paradigm for polymer dynamics in restrictive media. However, if a single chain is simultaneously trapped by many entropic traps, it has recently been suggested that the macromolecule does not undergo diffusion and is localized into a topologically frustrated dynamical state, in apparent violation of Einstein’s theorem. Using fluorescently labeled λ-DNA as the guest macromolecule embedded inside a similarly charged hydrogel with more than 95% water content, we present direct evidence for this new state of polymer dynamics at intermediate confinements. Furthermore, using a combination of theory and experiments, we measure the entropic barrier for a single macromolecule as several tens of thermal energy, which is responsible for the extraordinarily long extreme metastability. The combined theory–experiment protocol presented here is a determination of single-molecule entropic barriers in polymer dynamics. Furthermore, this method offers a convenient general procedure to quantify the underlying free energy landscapes behind the ubiquitous phenomenon of movement of single charged macromolecules in crowded environments.
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KIKUCHI, Yasuo. "Macromolecular complexes consisting of sodium tetrapolyphosphate with either fnctional organic macromolecule or inorganic macromolecules." NIPPON KAGAKU KAISHI, n. 6 (1987): 1086–88. http://dx.doi.org/10.1246/nikkashi.1987.1086.
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Zeugolis, D. I. "MACROMOLECULAR CROWDING AND OTHER IN VITRO MICROENVIRONMENT MODULATORS IN TENOCYTE CULTURES". Orthopaedic Proceedings 106-B, SUPP_2 (2 gennaio 2024): 71. http://dx.doi.org/10.1302/1358-992x.2024.2.071.
Testo completoAbstract (sommario):
The term macromolecular crowding is used to describe equilibria and kinetics of biochemical reactions and biological processes that occur via mutual volume exclusion of macromolecules in a highly crowded structureless medium. In vivo, the extracellular space is heavily crowded by a diverse range of macromolecules and thus, biological processes occur rapidly, whilst in vitro, in the absence of macromolecules, the same processes occur very slowly, if they are initiated at all (1-3). This talk will discuss the concept of macromolecular crowding, alone or in combination with other in vitro microenvironment modulators, in tendon engineering context.Acknowledgements: This work has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme, grant agreement No. 866126. This publication has emanated from research supported by grants from Science Foundation Ireland (SFI) under grant number 19/FFP/6982.
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Stepto, Robert, Taihyun Chang, Pavel Kratochvíl, Michael Hess, Kazuyuki Horie, Takahiro Sato e Jiří Vohlídal. "Definitions of terms relating to individual macromolecules, macromolecular assemblies, polymer solutions, and amorphous bulk polymers (IUPAC Recommendations 2014)". Pure and Applied Chemistry 87, n. 1 (1 gennaio 2015): 71–120. http://dx.doi.org/10.1515/pac-2013-0201.
Testo completoAbstract (sommario):
AbstractThis document defines terms relating to the properties of individual macromolecules, macromolecular assemblies, polymer solutions, and amorphous bulk polymers. In the section on polymer solutions and amorphous bulk polymers, general and thermodynamic terms, dilute solutions, phase behaviour, transport properties, scattering methods, and separation methods are considered. The recommendations are a revision and expansion of the IUPAC terminology published in 1989 dealing with individual macromolecules, macromolecular assemblies, and dilute polymer solutions. New terms covering the principal theoretical and experimental developments that have occurred over the intervening years have been introduced. Polyelectrolytes are not included.
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Collette, Dylan, David Dunlap e Laura Finzi. "Macromolecular Crowding and DNA: Bridging the Gap between In Vitro and In Vivo". International Journal of Molecular Sciences 24, n. 24 (15 dicembre 2023): 17502. http://dx.doi.org/10.3390/ijms242417502.
Testo completoAbstract (sommario):
The cellular environment is highly crowded, with up to 40% of the volume fraction of the cell occupied by various macromolecules. Most laboratory experiments take place in dilute buffer solutions; by adding various synthetic or organic macromolecules, researchers have begun to bridge the gap between in vitro and in vivo measurements. This is a review of the reported effects of macromolecular crowding on the compaction and extension of DNA, the effect of macromolecular crowding on DNA kinetics, and protein-DNA interactions. Theoretical models related to macromolecular crowding and DNA are briefly reviewed. Gaps in the literature, including the use of biologically relevant crowders, simultaneous use of multi-sized crowders, empirical connections between macromolecular crowding and liquid–liquid phase separation of nucleic materials are discussed.
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Juliano, R. "Challenges to macromolecular drug delivery". Biochemical Society Transactions 35, n. 1 (22 gennaio 2007): 41–43. http://dx.doi.org/10.1042/bst0350041.
Testo completoAbstract (sommario):
The use of macromolecules, particularly monoclonal antibodies, as therapeutic agents has come to the forefront in recent years. The biodistribution and delivery issues for protein drugs are shared to a substantial degree with other emerging therapeutic approaches including pharmacologically active nucleic acids and nanoparticles. A generalized approach to these issues involves consideration of the multiple biological barriers that stand between the macromolecular drug or nanoparticle at its site of administration and its ultimate biological target. Considerations of size, stability, non-specific versus specific associations and potency versus toxicity all play a role. The creation of delivery approaches that combine high specificity for the target cell or tissue, high therapeutic payload and modest toxicity remains a challenge, although some very promising examples have emerged recently. A variety of sophisticated targeting strategies, based primarily on combinatorial library methods, when used in combination with new technologies to identify cell-surface receptor ‘signatures’ of specific tissues, will facilitate advances in targeted delivery of macromolecules and nanoparticles. The challenges to contemporary macromolecule drug delivery are complex, thus new research paradigms are emerging that combine the talents of physical and biological scientists to address this key issue for modern pharmacology and therapeutics.
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Liao, Jinfang, Jack Diwu, Qin Zhao, Haitao Guo e Xing Han. "A new protein crosslinking method for labeling and modifying antibodies (TECH2P.758)". Journal of Immunology 194, n. 1_Supplement (1 maggio 2015): 206.4. http://dx.doi.org/10.4049/jimmunol.194.supp.206.4.
Testo completoAbstract (sommario):
Abstract The modification and labeling of a protein with a tag macromolecule is an important task in biological research. There are a few methods available for crosslinking two macromolecules. The direct crosslinking of two macromolecules suffer extremely low yield and difficult purification. A common method is to use a small crosslinker (such as SMCC) in numerous bioconjugations, but SMCC-modified protein is extremely unstable and often self-reactive during storage since proteins often contain both amine and thiol groups that cause significant amount of homo-crosslinking. We have recently developed an effective crosslinking method to selectively link two macromolecules. The new crosslinking method uses two unique crosslinkers that readily react upon mixing. Specifically, a pair of crosslinkers is used, including Buccutite FOL and Buccutite MTA. A protein (e.g., antibody) is first labeled with Buccutite FOL, and the tag macromolecule is labeled with Buccutite MTA. The two resulted Buccutite-modified conjugates can be readily purified by a desalting column or dialysis. Buccutite FOL-labeled protein and Buccutite MTA-tag macromolecule are mixed under extremely mild neutral conditions to give the desired protein-tag macromolecule conjugate. The Buccutite bioconjugation system is run at neutral pH, and completed within 1 hour. The conjugation can be run at low concentration, thus eliminating the pretreatment step for some diluted proteins. No catalyst is required.
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Gu, Li, Ning Wang, Leora M. Nusblat, Rose Soskind, Charles M. Roth e Kathryn E. Uhrich. "pH-responsive amphiphilic macromolecular carrier for doxorubicin delivery". Journal of Bioactive and Compatible Polymers 32, n. 1 (27 luglio 2016): 3–16. http://dx.doi.org/10.1177/0883911516643219.
Testo completoAbstract (sommario):
In this work, pH-sensitive amphiphilic macromolecules are designed to possess good biocompatibility and drug loading while employing an acid-sensitive linkage to trigger drug release at tumor tissues. Specifically, two pH-sensitive amphiphilic macromolecules were synthesized with a hydrazone linkage between the hydrophobic and hydrophilic segments. The chemical structure, molecular weight, critical micelle concentration, micelle size, and pH-triggered cleavage of the amphiphilic macromolecules were characterized via matrix-assisted laser desorption/ionization time-of-flight, nuclear magnetic resonance, and dynamic light scattering techniques. Drug loading and release as well as cytotoxicity studies were performed using doxorubicin. Hydrodynamic diameters of the micelles formed with pH-sensitive amphiphilic macromolecules were within an optimal range for cellular uptake. The critical micelle concentration values were 10–8–10–6 M, indicating micellar stability upon dilution. The degradation products of the amphiphilic macromolecules after acidic incubation were identified using mass spectrometry, nuclear magnetic resonance, and dynamic light scattering methods. A pH-dependent release profile of the doxorubicin-encapsulated amphiphilic macromolecules was observed. Cytotoxicity studies against two cancer cell lines, MDA-MB-231 human breast cancer cells and A549 lung cancer cells, showed that doxorubicin encapsulated in pH-sensitive amphiphilic macromolecules decreased cell viability more efficiently than free doxorubicin, possibly due to the toxicity of the amphiphilic macromolecule degradation products. Resulting from enhanced release at acidic pH due to hydrolysis of the hydrazone linkage, pH-sensitive amphiphilic macromolecules also had improved efficacy toward cancer cells compared to other carriers (e.g. Pluronics®). These findings indicate that pH-sensitive amphiphilic macromolecules can potentially be applied as anticancer drug delivery vehicles to achieve controlled release and improved therapeutic effects.
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Su, Jingqian, Shun Wu, Fen Zhou e Zhiyong Tong. "Research Progress of Macromolecules in the Prevention and Treatment of Sepsis". International Journal of Molecular Sciences 24, n. 16 (21 agosto 2023): 13017. http://dx.doi.org/10.3390/ijms241613017.
Testo completoAbstract (sommario):
Sepsis is associated with high rates of mortality in the intensive care unit and accompanied by systemic inflammatory reactions, secondary infections, and multiple organ failure. Biological macromolecules are drugs produced using modern biotechnology to prevent or treat diseases. Indeed, antithrombin, antimicrobial peptides, interleukins, antibodies, nucleic acids, and lentinan have been used to prevent and treat sepsis. In vitro, biological macromolecules can significantly ameliorate the inflammatory response, apoptosis, and multiple organ failure caused by sepsis. Several biological macromolecules have entered clinical trials. This review summarizes the sources, efficacy, mechanism of action, and research progress of macromolecular drugs used in the prevention and treatment of sepsis.
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Simionescu, M., L. Ghitescu, A. Fixman e N. Simionescu. "How Plasma Macromolecules Cross the Endothelium". Physiology 2, n. 3 (1 giugno 1987): 97–100. http://dx.doi.org/10.1152/physiologyonline.1987.2.3.97.
Testo completoAbstract (sommario):
Plasma macromolecules can, in some tissues, cross the capillary wall and enter the interstitial space by a specific mechanism of transcytosis in which a macromolecule is first recognized by its receptor on the luminal surface of endothelial cells. A cluster of receptors bearing their cargo is confined to a vesicle that crosses the cells and discharges the macromolecules on the abluminal surface. The process may be especially important for transport of large molecules, such as albumin, transferrin, insulin, and low-density-lipoprotein, to the cells where they are needed.
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Guillaumin, Salome, Mehmet Gurdal e Dimitrios I. Zeugolis. "Gums as Macromolecular Crowding Agents in Human Skin Fibroblast Cultures". Life 14, n. 4 (25 marzo 2024): 435. http://dx.doi.org/10.3390/life14040435.
Testo completoAbstract (sommario):
Even though tissue-engineered medicines are under intense academic, clinical, and commercial investigation, only a handful of products have been commercialised, primarily due to the costs associated with their prolonged manufacturing. While macromolecular crowding has been shown to enhance and accelerate extracellular matrix deposition in eukaryotic cell culture, possibly offering a solution in this procrastinating tissue-engineered medicine development, there is still no widely accepted macromolecular crowding agent. With these in mind, we herein assessed the potential of gum Arabic, gum gellan, gum karaya, and gum xanthan as macromolecular crowding agents in WS1 skin fibroblast cultures (no macromolecular crowding and carrageenan were used as a control). Dynamic light scattering analysis revealed that all macromolecules had negative charge and were polydispersed. None of the macromolecules affected basic cellular function. At day 7 (the longest time point assessed), gel electrophoresis analysis revealed that all macromolecules significantly increased collagen type I deposition in comparison to the non-macromolecular crowding group. Also at day 7, immunofluorescence analysis revealed that carrageenan; the 50 µg/mL, 75 µg/mL, and 100 µg/mL gum gellan; and the 500 µg/mL and 1000 µg/mL gum xanthan significantly increased both collagen type I and collagen type III deposition and only carrageenan significantly increased collagen type V deposition, all in comparison to the non-macromolecular crowding group at the respective time point. This preliminary study demonstrates the potential of gums as macromolecular crowding agents, but more detailed biological studies are needed to fully exploit their potential in the development of tissue-engineered medicines.
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Oliver, Susan, Orazio Vittorio, Giuseppe Cirillo e Cyrille Boyer. "Enhancing the therapeutic effects of polyphenols with macromolecules". Polymer Chemistry 7, n. 8 (2016): 1529–44. http://dx.doi.org/10.1039/c5py01912e.
Testo completo
27
Summers, J. C., L. Trais, R. Lajvardi, D. Hergan, R. Buechler, H. Chang, C. Pena-Rasgado e H. Rasgado-Flores. "Role of concentration and size of intracellular macromolecules in cell volume regulation". American Journal of Physiology-Cell Physiology 273, n. 2 (1 agosto 1997): C360—C370. http://dx.doi.org/10.1152/ajpcell.1997.273.2.c360.
Testo completoAbstract (sommario):
To gain insight into the mechanism(s) by which cells sense volume changes, specific predictions of the macromolecular crowding theory (A. P. Minton. In: Cellular and Molecular Physiology of Cell Volume Regulation, edited by K. Strange. Boca Raton, FL: CRC, 1994, p. 181-190. A. P. Minton, C. C. Colclasure, and J. C. Parker. Proc. Natl. Acad. Sci. USA 89: 10504-10506, 1992) were tested on the volume of internally perfused barnacle muscle cells. This preparation was chosen because it allows assessment of the effect on cell volume of changes in the intracellular macromolecular concentration and size while maintaining constant the ionic strength, membrane stretch, and osmolality. The predictions tested were that isotonic replacement of large macromolecules by smaller ones should induce volume decreases proportional to the initial macromolecular concentration and size as well as to the magnitude of the concentration reduction. The experimental results were consistent with these predictions: isotonic replacement of proteins or polymers with sucrose induced volume reductions, but this effect was only observed when the replacement was > or = 25% and the particular macromolecule had an average molecular mass of < or = 20 kDa and a concentration of at least 18 mg/ml. Volume reduction was effected by a mechanism identical with that of hypotonicity-induced regulatory volume decrease, namely, activation of verapamil-sensitive Ca2+ channels.
28
Tian, Dan, Chun-Hui He e Ji-Huan He. "Macromolecule Orientation in Nanofibers". Nanomaterials 8, n. 11 (7 novembre 2018): 918. http://dx.doi.org/10.3390/nano8110918.
Testo completoAbstract (sommario):
Electrospinning is now commercially used for the fabrication of nano/micro fibers. Compared with spider dragline silk, artificial fibers have poor mechanical properties. Unlike natural silk, which has a hierarchical structure with an approximate 3-fold symmetry, the molecular structure of spun fiber has neither folding nor orientation. To date, it is almost impossible to control molecule orientation during the spinning process. Here, we show that macromolecule orientation can be easily controlled using the laminar flow of fluid mechanics. A lasting laminar flow in a long needle can order macromolecules. We find that the orientation of macromolecules can greatly affect the morphology and mechanical properties of fibers. We expect our technology to be helpful for more sophisticated fabrication of fibers with ordered macromolecules and DNA-like twists.
29
Karmanov, Anatoly, Lyudmila Kocheva, Mikhail Borisenkov e Vladimir Belyi. "Macromolecular Hydrodynamics and Fractal Structures of the Lignins of Fir Wood and Oat Husks". Polymers 15, n. 17 (1 settembre 2023): 3624. http://dx.doi.org/10.3390/polym15173624.
Testo completoAbstract (sommario):
The topological structure of the macromolecules of lignins isolated from oat husk and fir wood was studied by means of macromolecular hydrodynamic methods. The macromolecular properties were analyzed by evaluating the intrinsic viscosity and coefficients of the translational diffusion and the sedimentation velocity of the lignins in dilute dimethylformamide solutions. The average molecular weights (MDη) and polydispersity parameters were calculated based on the results of the fractionation, as follows: Mw = 14.6 × 103, Mn = 9.0, and Mw/Mn = 1.62 for lignins from fir wood and Mw = 14.9 Mn = 13.5 and Mw/Mn = 1.1 for lignins from oat husks. The fractal analysis of the lignin macromolecules allowed us to identify the distinctive characteristics of the fractal and topological structures of these lignins. The measurements indicated that the fractal dimension (df) values of the guaiacyl-syringyl lignins from oat husks were between 1.71 and 1.85, while the df of a typical guaiacyl lignin from fir wood was ~2.3. Thus, we determined that the lignin macromolecules of oat husks belong to the diffusion-limited aggregation-type cluster–cluster class of fractals of the Meakin–Kolb type, with a predominance of characteristics common to a linear configuration. The lignins of softwood fir trees exhibited a branched topological structure, and they belong to the diffusion-limited aggregation-type particle–cluster class of fractals of the Witten–Sander type. Lignins from oat husks have the linear topology of macromolecules while the macromolecules of the lignins from fir wood can be characterized as highly branched polymers.
30
DUTKA, Volodymyr, e Nataliya OSHCHAPOVSKA. "THERMAL DECOMPOSITION OF THE PEROXIDE BONDS IN POLYMERS". Proceedings of the Shevchenko Scientific Society. Series Сhemical Sciences 2022, n. 70 (30 settembre 2022): 110–18. http://dx.doi.org/10.37827/ntsh.chem.2022.70.110.
Testo completoAbstract (sommario):
Peroxide-containing polymers containing diacyl peroxide groups in the main chain and in the side parts of macromolecules were obtained. The thermal decomposition of peroxide groups in macromolecules is well described by the first-order kinetic equation of rate. During the decomposition of O–O groups of polymers containing peroxide groups in the main chain, a decrease in the degree of polymerization of polymers is observed. The solvent in which the process takes place and the nature of the polymer-matrix, which contains peroxide groups, affects the rate of decomposition of peroxide groups and the degree of degradation of polymer macromolecules. Peroxide-containing polymers can be successfully used to obtain block copolymers, crosslinking agents, and macromolecular initiators.
31
Bremer, Anne, Ammon E. Posey, Madeleine B. Borgia, Wade M. Borcherds, Mina Farag, Rohit V. Pappu e Tanja Mittag. "Quantifying Coexistence Concentrations in Multi-Component Phase-Separating Systems Using Analytical HPLC". Biomolecules 12, n. 10 (14 ottobre 2022): 1480. http://dx.doi.org/10.3390/biom12101480.
Testo completoAbstract (sommario):
Over the last decade, evidence has accumulated to suggest that numerous instances of cellular compartmentalization can be explained by the phenomenon of phase separation. This is a process by which a macromolecular solution separates spontaneously into dense and dilute coexisting phases. Semi-quantitative, in vitro approaches for measuring phase boundaries have proven very useful in determining some key features of biomolecular condensates, but these methods often lack the precision necessary for generating quantitative models. Therefore, there is a clear need for techniques that allow quantitation of coexisting dilute and dense phase concentrations of phase-separating biomolecules, especially in systems with more than one type of macromolecule. Here, we report the design and deployment of analytical High-Performance Liquid Chromatography (HPLC) for in vitro separation and quantification of distinct biomolecules that allows us to measure dilute and dense phase concentrations needed to reconstruct coexistence curves in multicomponent mixtures. This approach is label-free, detects lower amounts of material than is accessible with classic UV-spectrophotometers, is applicable to a broad range of macromolecules of interest, is a semi-high-throughput technique, and if needed, the macromolecules can be recovered for further use. The approach promises to provide quantitative insights into the balance of homotypic and heterotypic interactions in multicomponent phase-separating systems.
32
Khan, Majad. "Chemical and Physical Architecture of Macromolecular Gels for Fracturing Fluid Applications in the Oil and Gas Industry; Current Status, Challenges, and Prospects". Gels 10, n. 5 (16 maggio 2024): 338. http://dx.doi.org/10.3390/gels10050338.
Testo completoAbstract (sommario):
Hydraulic fracturing is vital in recovering hydrocarbons from oil and gas reservoirs. It involves injecting a fluid under high pressure into reservoir rock. A significant part of fracturing fluids is the addition of polymers that become gels or gel-like under reservoir conditions. Polymers are employed as viscosifiers and friction reducers to provide proppants in fracturing fluids as a transport medium. There are numerous systems for fracturing fluids based on macromolecules. The employment of natural and man-made linear polymers, and also, to a lesser extent, synthetic hyperbranched polymers, as additives in fracturing fluids in the past one to two decades has shown great promise in enhancing the stability of fracturing fluids under various challenging reservoir conditions. Modern innovations demonstrate the importance of developing chemical structures and properties to improve performance. Key challenges include maintaining viscosity under reservoir conditions and achieving suitable shear-thinning behavior. The physical architecture of macromolecules and novel crosslinking processes are essential in addressing these issues. The effect of macromolecule interactions on reservoir conditions is very critical in regard to efficient fluid qualities and successful fracturing operations. In future, there is the potential for ongoing studies to produce specialized macromolecular solutions for increased efficiency and sustainability in oil and gas applications.
33
Krasteva, Maria, Saroj Kumar e Andreas Barth. "A dialysis accessory for attenuated total reflection infrared spectroscopy". Spectroscopy 20, n. 3 (2006): 89–94. http://dx.doi.org/10.1155/2006/186290.
Testo completoAbstract (sommario):
A dialysis accessory for attenuated total reflection (ATR) infrared spectroscopy is described together with an evaluation based on known systems with well-studied infrared spectra, such as chemical oxidation and reduction of cytochromecand substrate binding to the Ca2+-ATPase. Changes in the infrared spectra of the two proteins are successfully monitored with the dialysis accessory. The accessory was developed in our laboratory for the diamond 9-reflections SensIR ATR unit. It can be used to study absorbance changes of macromolecules which are induced by low molecular weight compounds, for example the binding of substrates, inhibitors or ions to macromolecules as well as effects of pH, ionic strength or denaturants on the structure of macromolecules. The dialysis accessory confines the macromolecule of interest to a sample compartment created between the ATR crystal and the dialysis membrane. On the other side of the dialysis membrane, a reservoir for the sample medium is created. In this way the low molecular weight compound of interest can exchange freely between the reservoir and the sample compartment via the dialysis membrane. This provides a flexible way to change sample conditions for the macromolecule of interest, allowing for example initiation of ligand binding.
34
Confer, David R., e Bruce E. Logan. "A conceptual model describing macromolecule degradation by suspended cultures and biofilms". Water Science and Technology 37, n. 4-5 (1 febbraio 1998): 231–34. http://dx.doi.org/10.2166/wst.1998.0631.
Testo completoAbstract (sommario):
Macromolecular (> 1,000 daltons) compounds such as proteins and polysaccharides can constitute a significant portion of dissolved organic carbon (DOC) in wastewater, but limited information is available on how these compounds are degraded in suspended and fixed-film biological wastewater treatment systems. Bacteria cannot assimilate intact macromolecules but must first hydrolyze them to monomers or small oligomers. Here, we summarize experiments performed in our laboratory which indicate that the enzymes responsible for hydrolysis are primarily those that remain attached to the cell. In biofilm cultures fed macromolecular substrates, for example, no more than 8% of total hydrolytic activity was found to be located in the cell-free bulk solution. These and other experiments support a generalized mechanism for macromolecule degradation by biofilms that features cell-associated hydrolysis, followed by the release of hydrolytic fragments back into bulk solution. The extent of fragment release is larger for proteins (bovine serum albumin) than for carbohydrates (dextrans).
35
Henneberg, Fabian, e Ashwin Chari. "Chromatography-Free Purification Strategies for Large Biological Macromolecular Complexes Involving Fractionated PEG Precipitation and Density Gradients". Life 11, n. 12 (24 novembre 2021): 1289. http://dx.doi.org/10.3390/life11121289.
Testo completoAbstract (sommario):
A complex interplay between several biological macromolecules maintains cellular homeostasis. Generally, the demanding chemical reactions which sustain life are not performed by individual macromolecules, but rather by several proteins that together form a macromolecular complex. Understanding the functional interactions amongst subunits of these macromolecular machines is fundamental to elucidate mechanisms by which they maintain homeostasis. As the faithful function of macromolecular complexes is essential for cell survival, their mis-function leads to the development of human diseases. Furthermore, detailed mechanistic interrogation of the function of macromolecular machines can be exploited to develop and optimize biotechnological processes. The purification of intact macromolecular complexes is an essential prerequisite for this; however, chromatographic purification schemes can induce the dissociation of subunits or the disintegration of the whole complex. Here, we discuss the development and application of chromatography-free purification strategies based on fractionated PEG precipitation and orthogonal density gradient centrifugation that overcomes existing limitations of established chromatographic purification protocols. The presented case studies illustrate the capabilities of these procedures for the purification of macromolecular complexes.
36
Krywko-Cendrowska, Agata, Dawid Szweda e Roza Szweda. "Well-Defined Conjugated Macromolecules Based on Oligo(Arylene Ethynylene)s in Sensing". Processes 8, n. 5 (3 maggio 2020): 539. http://dx.doi.org/10.3390/pr8050539.
Testo completoAbstract (sommario):
Macromolecules with well-defined structures in terms of molar mass and monomer sequence became interesting building blocks for modern materials. The precision of the macromolecular structure makes fine-tuning of the properties of resulting materials possible. Conjugated macromolecules exhibit excellent optoelectronic properties that make them exceptional candidates for sensor construction. The importance of chain length and monomer sequence is particularly important in conjugated systems. The oligomer length, monomer sequence, and structural modification often influence the energy bang gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the molecules that reflect in their properties. Moreover, the supramolecular aggregation that is often observed in oligo-conjugated systems is usually strongly affected by even minor structural changes that are used for sensor designs. This review discusses the examples of well-defined conjugated macromolecules based on oligo(arylene ethynylene) skeleton used for sensor applications. Here, exclusively examples of uniform macromolecules are summarized. The sensing mechanisms and importance of uniformity of structure are deliberated.
37
Khorolskyi, O. V., e Yu D. Moskalenko. "Calculation of the Macromolecular Size of Bovine Serum Albumin from the Viscosity of Its Aqueous Solutions". Ukrainian Journal of Physics 65, n. 1 (3 febbraio 2020): 41. http://dx.doi.org/10.15407/ujpe65.1.41.
Testo completoAbstract (sommario):
On the basis of experimental data for the shear viscosity of aqueous bovine serum albumin (BSA) solutions and in the framework of the Malomuzh–Orlov cellular approach, the surface of effective radii of BSA macromolecules has been plotted for the constant pH = 5.2 in the concentration interval of 2.0–27.2 wt% and the temperature interval 278–318 K. A rapid nonlinear increase in the effective radii of BSA macromolecules is shown to take place up to BSA concentrations of about 5 wt% in the whole examined temperature interval. The maxima of the effective radii of BSA macromolecules are observed at a BSA concentration of 5 wt%, and their position is temperature-independent. In the concentration interval 5.0–27.2 wt%, the effective radii of BSA macromolecules decrease, and this reduction is linear at BSA concentrations higher than 10 wt%. A comparison of the calculation results with literature data on the self-diffusion coefficient of macromolecules in solutions testifies to the efficiency of the Malomuzh–Orlov formula for calculating the macromolecular radii of globular proteins on the basis of shear viscosity data for their aqueous solutions.
38
Massey, Steven E., e Bud Mishra. "Origin of biomolecular games: deception and molecular evolution". Journal of The Royal Society Interface 15, n. 146 (settembre 2018): 20180429. http://dx.doi.org/10.1098/rsif.2018.0429.
Testo completoAbstract (sommario):
Biological macromolecules encode information: some of it to endow the molecule with structural flexibility, some of it to enable molecular actions as a catalyst or a substrate, but a residual part can be used to communicate with other macromolecules. Thus, macromolecules do not need to possess information only to survive in an environment, but also to strategically interact with others by sending signals to a receiving macromolecule that can properly interpret the signal and act suitably. These sender–receiver signalling games are sustained by the information asymmetry that exists among the macromolecules. In both biochemistry and molecular evolution, the important role of information asymmetry remains largely unaddressed. Here, we provide a new unifying perspective on the impact of information symmetry between macromolecules on molecular evolutionary processes, while focusing on molecular deception. Biomolecular games arise from the ability of biological macromolecules to exert precise recognition, and their role as units of selection, meaning that they are subject to competition and cooperation with other macromolecules. Thus, signalling game theory can be used to better understand fundamental features of living systems such as molecular recognition, molecular mimicry, selfish elements and ‘junk’ DNA. We show how deceptive behaviour at the molecular level indicates a conflict of interest, and so provides evidence of genetic conflict. This model proposes that molecular deception is diagnostic of selfish behaviour, helping to explain the evasive behaviour of transposable elements in ‘junk’ DNA, for example. Additionally, in this broad review, a range of major evolutionary transitions are shown to be associated with the establishment of signalling conventions, many of which are susceptible to molecular deception. These perspectives allow us to assign rudimentary behaviour to macromolecules, and show how participation in signalling games differentiates biochemistry from abiotic chemistry.
39
Dukes, Madeline J., Rebecca Thomas, John Damiano, Kate L. Klein, Sharavanan Balasubramaniam, Sanem Kayandan, Judy S. Riffle, Richey M. Davis, Sarah M. McDonald e Deborah F. Kelly. "Improved Microchip Design and Application for In Situ Transmission Electron Microscopy of Macromolecules". Microscopy and Microanalysis 20, n. 2 (13 dicembre 2013): 338–45. http://dx.doi.org/10.1017/s1431927613013858.
Testo completoAbstract (sommario):
AbstractUnderstanding the fundamental properties of macromolecules has enhanced the development of emerging technologies used to improve biomedical research. Currently, there is a critical need for innovative platforms that can illuminate the function of biomedical reagents in a native environment. To address this need, we have developed an in situ approach to visualize the dynamic behavior of biomedically relevant macromolecules at the nanoscale. Newly designed silicon nitride devices containing integrated “microwells” were used to enclose active macromolecular specimens in liquid for transmission electron microscopy imaging purposes.We were able to successfully examine novel magnetic resonance imaging contrast reagents, micelle suspensions, liposome carrier vehicles, and transcribing viral assemblies. With each specimen tested, the integrated microwells adequately maintained macromolecules in discrete local environments while enabling thin liquid layers to be produced.
40
Grube, Mandy, Gizem Cinar, Ulrich S. Schubert e Ivo Nischang. "Incentives of Using the Hydrodynamic Invariant and Sedimentation Parameter for the Study of Naturally- and Synthetically-Based Macromolecules in Solution". Polymers 12, n. 2 (31 gennaio 2020): 277. http://dx.doi.org/10.3390/polym12020277.
Testo completoAbstract (sommario):
The interrelation of experimental rotational and translational hydrodynamic friction data as a basis for the study of macromolecules in solution represents a useful attempt for the verification of hydrodynamic information. Such interrelation originates from the basic development of colloid and macromolecular science and has proven to be a powerful tool for the study of naturally- and synthetically-based, i.e., artificial, macromolecules. In this tutorial review, we introduce this very basic concept with a brief historical background, the governing physical principles, and guidelines for anyone making use of it. This is because very often data to determine such an interrelation are available and it only takes a set of simple equations for it to be established. We exemplify this with data collected over recent years, focused primarily on water-based macromolecular systems and with relevance for pharmaceutical applications. We conclude with future incentives and opportunities for verifying an advanced design and tailored properties of natural/synthetic macromolecular materials in a dispersed or dissolved manner, i.e., in solution. Particular importance for the here outlined concept emanates from the situation that the classical scaling relationships of Kuhn–Mark–Houwink–Sakurada, most frequently applied in macromolecular science, are fulfilled, once the hydrodynamic invariant and/or sedimentation parameter are established. However, the hydrodynamic invariant and sedimentation parameter concept do not require a series of molar masses for their establishment and can help in the verification of a sound estimation of molar mass values of macromolecules.
41
Weik, Martin, e Jacques-Philippe Colletier. "Temperature-dependent macromolecular X-ray crystallography". Acta Crystallographica Section D Biological Crystallography 66, n. 4 (24 marzo 2010): 437–46. http://dx.doi.org/10.1107/s0907444910002702.
Testo completoAbstract (sommario):
X-ray crystallography provides structural details of biological macromolecules. Whereas routine data are collected close to 100 K in order to mitigate radiation damage, more exotic temperature-controlled experiments in a broader temperature range from 15 K to room temperature can provide both dynamical and structural insights. Here, the dynamical behaviour of crystalline macromolecules and their surrounding solvent as a function of cryo-temperature is reviewed. Experimental strategies of kinetic crystallography are discussed that have allowed the generation and trapping of macromolecular intermediate states by combining reaction initiation in the crystalline state with appropriate temperature profiles. A particular focus is on recruiting X-ray-induced changes for reaction initiation, thus unveiling useful aspects of radiation damage, which otherwise has to be minimized in macromolecular crystallography.
42
Li, Yue, Jinlian Duan, Heng Xia, Bin Shu e Weigang Duan. "Macromolecular substances as a dangerous factor in traditional Chinese medicine injections were determined by size-exclusive chromatography". Toxicology Research 9, n. 3 (21 maggio 2020): 323–30. http://dx.doi.org/10.1093/toxres/tfaa024.
Testo completoAbstract (sommario):
Abstract Macromolecular substances in traditional Chinese medicine injections (TCMIs) are expected to be a main dangerous factor causing anaphylactic or anaphylactoid reaction. The main aim of the study was to verify the macromolecular substances’ anaphylactic or anaphylactoid reaction in guinea pigs and establish a size-exclusive chromatographic method to detect them. The macromolecular substances from six TCMIs (Danshen injection, Dengzhanxixin injection, Honghua injection, Qingkailing injection, Shuanghuanglian injection and Shuxuening injection) were prepared by removing substances with molecular weight less than 10 kDa with an ultra-filter. The anaphylactic and anaphylactoid reactions caused by original TCMIs, injections rich in or free of macromolecules were assayed in guinea pigs. The relationship between the amount of the macromolecular substances and peak area of chromatogram was established by size-exclusive chromatography. Injections free of macromolecules were not likely to cause anaphylactic and anaphylactoid reactions, but injections rich in macromolecular substances were more likely to do so. If the macromolecular substances with molecular weight bigger than 10 kDa were removed, the signal of macromolecular substances in TCMIs was quantitatively reduced. All the results suggested that macromolecular substances in TCMIs are a dangerous factor causing safety problems, and the macromolecular substances can be quantitatively detected with size-exclusive chromatography.
43
Penn, M. S., S. Rangaswamy, G. M. Saidel e G. M. Chisolm. "Macromolecular transport in the arterial intima: comparison of chronic and acute injuries". American Journal of Physiology-Heart and Circulatory Physiology 272, n. 4 (1 aprile 1997): H1560—H1570. http://dx.doi.org/10.1152/ajpheart.1997.272.4.h1560.
Testo completoAbstract (sommario):
Hypertension is a known risk factor for the development of atherosclerosis, which is characterized by the abnormal accumulation of low-density lipoprotein and other plasma-borne macromolecules. The goal of this study was to measure accumulation of a plasma-borne macromolecular marker, horseradish peroxidase (HRP; 44 kDa), in the aortic intima and media of chronically hypertensive rats. HRP transport in 2-yr-old spontaneously hypertensive rats (SHR) was compared with that in age-matched Wistar-Kyoto rats (WKY) under conditions in which blood pressures were not significantly different during the 15-min HRP circulation. Intimal accumulation and medial HRP concentration profiles were obtained from methacrylate-embedded sections after reaction with 3,3'-diaminobenzidine and H2O2. Data were analyzed using a mathematical model of macromolecular transport to quantify the permeabilities of endothelium and internal elastic lamina (IEL). Chronic hypertension increased endothelial permeability without a change in IEL permeability. An apparent convective flux of HRP into the intima of SHR raised intimal HRP to a concentration higher than that of HRP in the plasma. Our results suggest that the intimal accumulation of plasma-borne macromolecules from pressure-driven convection is normally minimized by an intact endothelium. Similar changes resulted from acute injury by lipopolysaccharide, suggesting endothelial injury could account for transport changes associated with hypertension. After either chronic or acute endothelial damage, transport of macromolecules into the intima increases, but the IEL continues to retard transport of macromolecules beyond the intima, resulting in increased intimal accumulation.
44
C.M.D. "Macromolecular structures 1991: Atomic structures of biological macromolecules". Trends in Biochemical Sciences 17, n. 7 (luglio 1992): 272. http://dx.doi.org/10.1016/0968-0004(92)90412-3.
Testo completo
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Holloway, Joshua O., Filip Van Lijsebetten, Nezha Badi, Hannes A. Houck e Filip E. Du Prez. "From Sequence‐Defined Macromolecules to Macromolecular Pin Codes". Advanced Science 7, n. 8 (3 marzo 2020): 1903698. http://dx.doi.org/10.1002/advs.201903698.
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Kranc, Wiesława, Piotr Celichowski, Joanna Budna, Ronza Khozmi, Artur Bryja, Sylwia Ciesiółka, Marta Rybska et al. "Positive Regulation of Macromolecule Metabolic Process Belongs to the Main Mechanisms Crucial for Porcine Oocytes Maturation". Advances in Cell Biology 5, n. 1 (1 marzo 2017): 15–31. http://dx.doi.org/10.1515/acb-2017-0002.
Testo completoAbstract (sommario):
SummaryThe mammalian oocytes maturation is the compound process that involves morphological and molecular changes. These modifications include storage of macromolecules, which are crucial for proteins biosynthesis during periimplantation stages of embryo development. This study was aimed to investigate the genes expression profile encoding macromolecules important for regulation of proper porcine oocytes maturation.The porcine oocytes were collected from large ovarian follicles and analyzed both before and after in vitro maturation (IVM). Additionally, to check the developmental competence status, brilliant crezyl blue test (BCB) was performed. The obtained cDNA was used for biotin labeling and fragmentation by AffymetrixGeneChip® WT Terminal Labeling and Hybridization (Affymetrix). The preliminary analysis of the scanned chips was performed using AffymetrixGeneAtlasTM Operating Software. The created CEL files were imported into downstream data analysis software.In results, we found expression of 419 different genes, 379 genes were down-regulated and 40 genes were up-regulated in relation to the oocyte transcriptome before in vitro procedure. We observed up-regulation of all genes involved in “positive regulation of macromolecule metabolic process” before IVM as compared to transcriptional profile analyzed after IVM.In conclusion, we suggested that genes encoding proteins involved in macromolecule metabolism are important for achieving of porcine oocytes maturational stage. Moreover, the “activity of macromolecules metabolism” is much more increased in immature oocytes.
47
Gilliland, Gary L., Michael Tung e Jane E. Ladner. "The Biological Macromolecule Crystallization Database: crystallization procedures and strategies". Acta Crystallographica Section D Biological Crystallography 58, n. 6 (29 maggio 2002): 916–20. http://dx.doi.org/10.1107/s0907444902006686.
Testo completoAbstract (sommario):
The Biological Macromolecule Crystallization Database (BMCD) archives crystallization data from published reports for all forms of biological macromolecules that have produced crystals suitable for X-ray diffraction studies. The information includes the crystallization conditions, crystal data, comments about the crystallization procedure and information on the biological macromolecule or biological macromolecule complex. Crystallization procedures, including fast screens and more general procedures, can be developed effectively using this web-based resource (http://wwwbmcd.nist.gov:8080/bmcd/bmcd.html).
48
Stewart, Murray. "Function of the Nuclear Transport Machinery in Maintaining the Distinctive Compositions of the Nucleus and Cytoplasm". International Journal of Molecular Sciences 23, n. 5 (25 febbraio 2022): 2578. http://dx.doi.org/10.3390/ijms23052578.
Testo completoAbstract (sommario):
Although the separation of transcription and translation, mediated by the nuclear envelope, is the defining characteristic of Eukaryotes, the barrier between the nuclear and cytoplasmic compartments needs to be semipermeable to enable material to be moved between them. Moreover, each compartment needs to have a distinctive complement of macromolecules to mediate specific functions and so movement between them needs to be controlled. This is achieved through the selective active transport of macromolecules through the nuclear pores that stud the nuclear envelope, and which serve as a conduit between these compartments. Nuclear pores are huge cylindrical macromolecular assemblies and are constructed from the order of 30 different proteins called nucleoporins. Nuclear pores have a central transport channel that is filled with a dense network of natively unfolded portions of many different nuclear pore proteins (nucleoporins or nups). This network generates a barrier that impedes, but does not entirely prevent, the diffusion of many macromolecules through the pores. The rapid movement of a range of proteins and RNAs through the pores is mediated by a range of transport factors that bind their cargo in one compartment and release it in the other. However, although as their size increases the diffusion of macromolecules through nuclear pores is progressively impaired, additional mechanisms, including the binding of some macromolecules to immobile components of each compartment and also the active removal of macromolecules from the inappropriate compartment, are needed to fully maintain the distinctive compositions of each compartment.
49
Augustin, S., H. Wex, D. Niedermeier, B. Pummer, H. Grothe, S. Hartmann, L. Tomsche et al. "Immersion freezing of birch pollen washing water". Atmospheric Chemistry and Physics 13, n. 21 (11 novembre 2013): 10989–1003. http://dx.doi.org/10.5194/acp-13-10989-2013.
Testo completoAbstract (sommario):
Abstract. Birch pollen grains are known to be ice nucleating active biological particles. The ice nucleating activity has previously been tracked down to biological macromolecules that can be easily extracted from the pollen grains in water. In the present study, we investigated the immersion freezing behavior of these ice nucleating active (INA) macromolecules. Therefore we measured the frozen fractions of particles generated from birch pollen washing water as a function of temperature at the Leipzig Aerosol Cloud Interaction Simulator (LACIS). Two different birch pollen samples were considered, with one originating from Sweden and one from the Czech Republic. For the Czech and Swedish birch pollen samples, freezing was observed to start at −19 and −17 °C, respectively. The fraction of frozen droplets increased for both samples down to −24 °C. Further cooling did not increase the frozen fractions any more. Instead, a plateau formed at frozen fractions below 1. This fact could be used to determine the amount of INA macromolecules in the droplets examined here, which in turn allowed for the determination of nucleation rates for single INA macromolecules. The main differences between the Swedish birch pollen and the Czech birch pollen were obvious in the temperature range between −17 and −24 °C. In this range, a second plateau region could be seen for Swedish birch pollen. As we assume INA macromolecules to be the reason for the ice nucleation, we concluded that birch pollen is able to produce at least two different types of INA macromolecules. We were able to derive parameterizations for the heterogeneous nucleation rates for both INA macromolecule types, using two different methods: a simple exponential fit and the Soccer ball model. With these parameterization methods we were able to describe the ice nucleation behavior of single INA macromolecules from both the Czech and the Swedish birch pollen.
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Faizah, Az-Zafira Syairul, Julia Mardhiya e Fachri Hakim. "DESIGNING A CHEMO-ENTREPRENEURSHIP PRACTICAL INSTRUCTION IN THE TOPIC OF MACROMOLECULES". Jurnal Pena Sains 11, n. 1 (28 aprile 2024): 34–41. http://dx.doi.org/10.21107/jps.v11i1.20183.
Testo completoAbstract (sommario):
The CEP approach combines chemical knowledge with entrepreneurial concepts. In the manufacture of macromolecular products, a deep understanding of chemistry is essential. Entrepreneurship education is very important because it raises enthusiasm and motivates students to start a business when they graduate from school. The research objective is to design practical instruction for Chemo-Entrepreneurship (CEP) focusing on the subject of macromolecules. The type of research used for the development of practical instructions in this study is Research and Development. The development method is ADDIE (Analysis, Design, Development, Implementation, and Evaluation). The product developed was validated by six validators in the valid category according to Aiken's V table with a validity value of 0.846. The research subjects in the product trial developed in this study were students of class XII MIPA SMAN 1 Cepu. The assessment of student responses was in the very good category with a percentage of 94.3%. It can be concluded that the CEP-practical guide is feasible to use. The resulting product is expected to be used as a learning resource on the macromolecule topic.