Ukrainskii biokhimicheskii zhurnal (1978)最新文献

From epithelial layer of rat intestinal were selected water soluble substances which influenced on Na+,K(+)-ATPase activity in 2 different ways: substances with molecular weight 220 Da, 400 Da were its activators, substance with weight 150 Da-inhibitor. Na+,K(+)-ATPase activators preincubated previously with Na+ acquire properties of inhibitors. Bivalent cations Ca, Mg remove this effect of Na-ions.

Effects of water-soluble form of linoleic-hydroxamic acid, inhibitor of lipoxygenase, on process of atherogenesis (alimentary model) were studied at rabbits. It was shown that inhibition of activity of lipoxygenase during process of development of atherosclerosis led to considerable decrease of area of lipoid plaques and lipoidosis, decreased content of cholesterol in blood and improved free-radical modification of lipoproteins of blood.

The review is devoted to hypercholesterolemia which is one of the leading risk factors for IHD. By its origin it can be primary and secondary. Three major mechanisms of primary hypercholesterolemia in humans are discussed. They are: low activity of LDL receptors, reduced affinity of LAL for receptors and overproduction of lipoproteins containing apo B. Depending on mechanism nonidentical molecular defects leading to cholesterol imbalance in cells or in circulating lipoproteins are occurred. The understanding of the nature and mechanisms of hypercholesterolemia development is of great clinical value, because having determined molecular defect and using drugs combinations the majority of patients are a success to have their lipids normal. Only in the case of homozygous familial hypercholesterolemia medicamentous treatment becomes secondary and the principal therapeutic methods are plasmapheresis or selective LDL apheresis. Gene therapy as a method of homozygous familial hypercholesterolemia correction is in forthcoming future.

Collagen constitutes approximately one third of the body's proteins; it has different functions, and changes in its metabolism and structure accompany almost every pathologic process. This article reviews basic knowledge of the alterations and defects in collagen metabolism and structure which give rise to a number of heritable and acquired diseases, their causes and consequences.

Isolation of highly purified and highly molecular monoamine oxidase (MAO) from pig liver mitochondria have been worked out. Specific activity of isolated preparation is 2700 times higher than of original mitochondria homogenate. Enzyme solubilization by digitonin, affinity chromatography purification and ultrafiltration underlie this method. MAO catalytic properties changing during the process of purification by different methods have been investigated. Substrate specificity was studied; kinetic parameters of enzymatic desemination were calculated.

The role of adenosine on the regulation of mitochondrial function has been studied. In order to evaluate this the following experiments were done in isolated rat cardiomyocites and mitochondria using polarographic techniques. Cardiomyocyte oxygen consumption (MVO2) and mitochondrial respiratory function (State 3 and State 4, respiratory control index, and ADP/O ratio) were evaluated after exposure to adenosine. Cardiomyocyte MVO2 was significantly lower in cells previously exposed to adenosine (10 microM, 15 min or 30 min cell incubation) than in cells not exposed to adenosine (control). Addition of dipyridamole (10 microM) or 8-(p-Sulfophenyl) theophylline (50 microM) to cardiomyocytes before adenosine incubation prevented the adenosine-induced changes in MVO2. Mitochondria obtained from isolated perfused beating heart previously perfused with adenosine (10 microM, 30 min heart perfusion) also resulted in significant increases in ADP/O and respiratory control index compared to matching control. Mitochondria isolated from cardiomyocytes previously exposed to adenosine (10 microM, 15 min or 30 min cell incubation) resulted in a significant increase in mitochondrial ADP/O ratio compared to control. Adenosine-induced decrease in cardiomyocyte MVO2 may be related to an increase in efficiency of mitochondrial oxidative phosphorylation, and more economical use of oxygen, which is necessary for survival under ischemic stress.

Kinetics of methemoglobin structural changes in the complex with liposomes composed of phosphatidylcholine and its mixtures with cardiolipin has been studied. The amplitudes and rate constants of the two observed kinetic phases are determined. The fast kinetic phase is attributed to the formation of the unstable intermediate protein form, while the slow one is assumed to reflect dissociation of the heme--globin complex.

It is shown that giving rats natural water "Naftusya" to drink during 5 days initiated a complex of variations in change of substances, conditioned by general adaptational reaction. Ultraviolet radiation of water has no effect on its balneoactivity while ultrafiltration attenuates it a little.

Phosphorylation of myosin regulatory light chain (RLC) catalysed by myosin light chain kinase (MLCK) is a key reaction in the regulation of actin-myosin interaction in smooth muscle. The activation of MLCK by calmodulin (CaM) and Ca2+ was investigated over a wide range of the enzyme concentrations using myosin or its RLC with Mw = 20 kDa as substrates. Kinase activation by CaM (at saturating Ca2+ concentrations) was characterized by positive cooperativity even though noncooperative activation would be expected from the established 1:1 binding stoichiometry between MLCK and CaM. The activation of the kinase by Ca2+ was also cooperative but only at relatively low CaM levels. This cooperativity was shown to result from time dependent changes in MLCK that take place during its incubation with Ca2+ and CaM before substrate addition in phosphorylation assays. As a result the kinase activity as a function of its concentration at constant CaM level was biphasic: there was the activity optimum at 1:1 ratio of CaM to MLCK and almost complete inhibition at 3 to 7 molar excess of kinase over CaM. Such changes that take place during 10 to 15 min preincubation with Ca2+ and CaM may involve the kinase supramolecular structure formation or/and its conformational rearrangements.

Recent data about the structural and functional features of protein motors (myosin, dynein, kinesin) are presented. The mechanism by which the chemical energy of ATP is transduced into mechanical work is discussed.