Biomedical subjects
Publications and source records attributed to T I Bogacheva.
A simple and rapid method for determination of the activity of beta-lactamase is described. It is based on spectrophotometric recording of the enzymatic splitting of benzylpenicillin. The method is recommended for rapid control of production of beta-lactamase inhibitors.
A comparative study of terrylytin, trypsin and products of their covalent binding to human serum albumin was carried out. Modification caused a decrease of the affinity of both enzymes for proteinase inhibitors from the blood. The inhibition constant for terrylytin was increased 3-4-fold, that for trypsin - by 2 or 3 orders. The recalcification time of human blood plasma in the presence of terrylytin remained practically unchanged after enzyme chemical modification. Trypsin binding to albumin decreased its coagulability. Preparations of modified enzymes were characterized by a decreased acute toxicity, this effect being especially well-pronounced in the case of trypsin. The decrease of terrylytin toxicity due to modification can be accounted for by a decrease in its affinity for alpha2-macroglobulin. The decrease of trypsin toxicity is apparently due to a decrease of its coagulability due to binding to albumin.
Physico-chemical properties of trypsin covalently bound with human serum albumin by glutaric aldehyde have been studied. The modification of the enzyme practically caused no changes in the pH optimum of trypsin. The inhibition of modified trypsin by inhibitors from soy beans and human blood serum has been also studied. The apparent inhibition constants have been calculated. The modification has been shown to result in a deceleration of autolytic degradation. The autolysis rate constants have been calculated at 50 degrees C.
We have measured the alpha-deuterium and alpha-tritium secondary kinetic isotope effects on the synthesis and phosphorolysis of glycogen catalyzed by glycogen phosphorylase B (EC 2.4.1.1). The isotope-labeled substrates glucose-1T-1-phosphate and 1C14-glucose-1D-1-phosphate were used in the experiments, together with 6T-glucose-1-phosphate and C14-glucose-1-phosphate as controls. Measurement by the double label technique showed that both effects studied were equal to zero within the limits of experimental error. The possible mechanism of action of phosphorylase B is discussed.
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This paper describes a graphic method for measuring the affinity and molar concentration of proteinase inhibitors from different sources, using data on the titration of the inhibitor by the enzyme of a known molar concentration. Linearization of experimental data in the (formula; see text) coordinates makes it possible to measure the value Ki with respect to the slope of the curve and to determine the inhibitor concentration with respect to the curve intercept with the ordinate axis. The method can be used to characterize proteinase inhibitors during microbial screening and at certain purification stages.
The molecular weight distribution, thermal stability during autolysis, resistance to human serum inhibitors as well as temperature optimum of native and dextran-modified trypsin were investigated. The seeming constants of autolytic inactivation and inhibition of native and modified trypsin were calculated. Trypsin polymer derivatives had higher molecular weight than the native enzyme. They also showed higher resistance to autolysis and serum inhibitors. Possible causes of the above effects are discussed.