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001-es BibID:	BIBFORM005993
Első szerző:	Somogyi Béla (biofizikus)
Cím:	The dynamic basis of energy transduction in enzymes / Béla Somogyi, G. Rickey Welch, Sándor Damjanovich
Dátum:	1984
ISSN:	0304-4173
Megjegyzések:	The most important idea underlying our treatment herein is the unity of the enzyme molecule and the medium. Appreciation of this relationship is vital, if enzymology is to graduate from its present reductionistic status to a more holistic posture. Enzymes are biological entities firstly, and isolated objects of physicochemical analysis secondly. Perhaps the most crucial 'biological lesson', particularly apropos of enzymes in intermediary metabolism, concerns the 'cytosociology' of enzyme action in vivo [94,128]. The natural habitat of many enzymes in the living cell is far different from that in bulk aqueous solution in vitro. In order to obtain a real grasp of the nature of enzyme function, one must ultimately couch enzymology in concepts emerging from contemporary cell biology [95]. Notwithstanding, analysis precedes synthesis; and one must needs begin with the individual enzyme molecule. The trenchant efforts of the physical chemist and the organic chemist have produced a wealth of information on the nature of the binding and catalytic events at the enzyme active site. While it is not yet possible to explain precisely the complete sequence of events in the catalytic process, nevertheless, the basic mechanisms by which enzymes effect catalysis (i.e., reduce activation energy) now seem apparent [81,129]. The new frontier is to be found, in exploring the dynamic role of the protein matrix [17]. Not only does the protein provide the 3-D scaffolding for active-site processes, but, more importantly, it serves as the local solvent for the bound chemical subsystem. Thus, the dynamical aspects of enzyme catalysis (for thermally based systems) must arise from the fluctuational properties of the protein molecule. This notion is the common denominator in all of the models in subsection IIC. It is the anisotropic nature of this fluctuational behavior, which would characterize the energy-transduction phenomenon leading to localized catalytic events at the active-site. In Section III we attempted to show that all of the various enzyme models contribute pieces to a single, all-embracing jig-saw puzzle. Some models focus on the dynamical properties of the protein per se, whereas others deal with the stochastic aspects of protein-solvent interaction. The two approaches are complementary, as are mutually interlocking pieces of a puzzle. The ultimate picture depicted by this 'jig-saw puzzle' is still somewhat vague--owing to the present paucity of empirical information on protein motions.(ABSTRACT TRUNCATED AT 400 WORDS)
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban analysis Binding Sites Catalysis chemistry Cytoplasm Diffusion Electrochemistry Energy Metabolism Enzymes enzymology Hydrogen Bonding In Vitro Kinetics metabolism Models,Biological Protein Conformation Protons Solvents Thermodynamics Viscosity Water
Megjelenés:	Biochimica et Biophysica Acta (BBA). Reviews on Bioenergetics. - 768 : 2 (1984), p. 81-112. -
További szerzők:	Welch, Rickey G. Damjanovich Sándor (1936-2017) (biofizikus)
Internet cím:	Intézményi repozitóriumban (DEA) tárolt változat DOI Szerző által megadott URL
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001-es BibID:	BIBFORM006057
Első szerző:	Vereb György (biofizikus, orvos)
Cím:	Effect of cyclosporin A on the membrane potential and Ca2+ level of human lymphoid cell lines and mouse thymocytes / György Vereb Jr., György Panyi, Margit Balázs, László Mátyus, János Matkó, Sándor Damjanovich
Dátum:	1990
ISSN:	0005-2728
Megjegyzések:	The effect of the immunosuppressive cyclosporin A (CsA) on the cytosolic free Ca2+ concentration ([Ca2+]i) and membrane potential of human B and T lymphoblastoid cells and mouse thymocytes was studied in order to reveal some features of the early stage of drug-cell interaction. Cytosolic free Ca2+ concentration of the cells was measured by spectrofluorimetry using indo-1 and quin2 fluorescent calcium indicators. Membrane potential was monitored in a flow cytometer with oxonol dye. CsA applied at 2-20 micrograms/ml final concentrations caused a dose-dependent, rapid, transient rise of [Ca2+]i in all cell types. This effect could be blocked by chelating the extracellular Ca2+ with EGTA but was not sensitive to Ca2+ channel blockers verapamil and nifedipine or K+ channel blocker 4-aminopyridine. A possible explanation for the calcium mobilizing effect of CsA is an ionophore-like mode of action at the cell membrane level. Besides directly interfering with mitogenic signals, the elevation of [Ca2+]i could be responsible for an initial hyperpolarization observed in CsA-treated T lymphocytes. This hyperpolarization, however, was not detectable in B lymphoblastoid cells. A further difference between B and T cells was the diverse pattern of depolarization following CsA treatment. This variance in the behaviour of T and B lymphocytes and the diversity of membrane transport systems in its background could account for the different final outcome of the drug-cell interaction.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban Cyclosporin A Indo-1 Quin2 Membrane potential Human lymphoid cell lines Mouse thymocytes
Megjelenés:	Biochimica et Biophysica Acta (BBA). Bioenergetics. - 1019 : 2 (1990), p. 159-165. -
További szerzők:	Panyi György (1966-) (biofizikus) Balázs Margit (1952-) (sejtbiológus, molekuláris genetikus) Mátyus László (1956-) (biofizikus) Matkó János (1952-) (biológus) Damjanovich Sándor (1936-2017) (biofizikus)
Internet cím:	Szerző által megadott URL DOI Intézményi repozitóriumban (DEA) tárolt változa
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