ABSTRACT
The protective effects of 70-kDa heat shock proteins (HSP70) were studied following the intravenous administration in rats with endotoxic shock. The antitoxic effects of both bovine HSP70 (bHSP70) and human recombinant HSP70 (hrHSP70) were compared. The preventive uptake of HSP70 decreased the toxic influence of the E. coll endotoxin on the rats' bodies and significantly increased the survival of the animals during the experiment.
Subject(s)
HSP70 Heat-Shock Proteins/pharmacology , Shock, Septic/blood , Animals , Cattle , Dose-Response Relationship, Drug , Escherichia coli , HSP70 Heat-Shock Proteins/therapeutic use , Humans , Lipopolysaccharides/pharmacology , Male , Rats , Recombinant Proteins/pharmacology , Recombinant Proteins/therapeutic use , Shock, Septic/drug therapy , Shock, Septic/mortalityABSTRACT
The effect of sugar and its phosphate derivatives on sorbitoldehydrogenase from bovine liver has been studied. The presence of 100 mM glucose, mannose, and arabinose did not influence that activity of the studied reaction, whereas fructose, sorbose, and xylose, inhibit the reaction by 20-25%. This can be explained in terms of inhibition by the final reaction products. Inhibition by glucose-6-phosphate (24%), glucose-1-phosphate (21%), and fructose-6-phosphate (42%) is of particular interest since these compounds may play a regulatory role.
Subject(s)
Carbohydrates/pharmacology , L-Iditol 2-Dehydrogenase/metabolism , Liver/drug effects , Animals , Cattle , Cytoplasm/drug effects , Cytoplasm/enzymology , Liver/enzymology , Male , Sugar Phosphates/pharmacologyABSTRACT
The kinetic properties of sorbitol dehydrogenase from calf liver cell cytoplasm during sorbitol oxidation were studied at pH 7.0, 7.5, 8.0, 9.0 and 10.0. It was found that the shape of kinetic curves for NADH accumulation depends on pH and substrate concentration. At pH 7.0, 7.5 and 8.0 the enzymatic reaction obeys the Michaelis-Menten kinetics with Km of 3.3 x 10(-3) M. 2.3 x 10(-3) M and 2.08 x 10(-3) M, respectively. At pH 9.0 and 10.0 the vovs [So] curves have an "intermediate plateau". The Hill plots for this reaction reveal two slopes that are dependent on substrate concentration. The nH values for sorbitol (up to 2 mM) are 1.0 and 1.16 at pH 9.0 and 10.0, respectively. With a further rise in the substrate concentration, the nH value increases up to 2.4 and 2.18 at pH 9.0 and 10.0, respectively. This is suggestive of the existence of a slowly dissociating enzymatic system of the Np in equilibrium P type (where P is the oligomeric and p the monomeric forms of the enzyme); N approximately greater than 2. The vovs NAD plots are S-shaped at all pH values studied. The data obtained are discussed in terms of regulatory effects of sorbitol and acidity on association-dissociation of sorbitol dehydrogenase from liver cell cytoplasm.
Subject(s)
L-Iditol 2-Dehydrogenase/metabolism , Liver/enzymology , Sugar Alcohol Dehydrogenases/metabolism , Animals , Catalysis , Cattle , Cytoplasm/enzymology , Hydrogen-Ion Concentration , Kinetics , Substrate SpecificityABSTRACT
A comparative study of sorbitol dehydrogenase activity in bovine, calf, and rat liver cell cytoplasm has been carried out. The level of activity of the enzyme is several times greater than that of marker enzymes (alcohol dehydrogenase, glucose-6-phosphate dehydrogenase). The data obtained suggest that the polyol (sorbitol) metabolism pathway of glucose functions actively in mammalian liver cells.
Subject(s)
Cytoplasm/enzymology , L-Iditol 2-Dehydrogenase/metabolism , Liver/enzymology , Sugar Alcohol Dehydrogenases/metabolism , Alcohol Oxidoreductases/metabolism , Animals , Cattle , Glucose/metabolism , Glucosephosphate Dehydrogenase/metabolism , Male , Rats , Rats, Inbred StrainsABSTRACT
Partially purified preparation of sorbitol dehydrogenase, isolated from hepatocytes of bovine liver tissue, was active at a wide range of pH exhibiting the maximal activity at pH 9.0 in presence of NAD but not of NADP. The high rate of sorbitol and xylitol dehydration was observed, whereas the enzyme dehydrated ribitol at the 4-fold lower rate. Disc electrophoresis of the preparation in polyacrylamide gel, where sorbitol, xylitol and ribitol were used as substrates for colorimetric detection of the enzyme activity, exhibited six enzymatic zones with Rf 0.387, 0.266, 0.338, 0.193, 0.129 and 0.064. Optimal conditions were developed for storage of the active enzyme.