Biomedical subjects
Publications and source records attributed to N V Kukushkina.
Using low temperature EPR spectroscopy, signals of iron-sulfur centers with g-factors of 2.02 and 1.94 were detected in the respiratory chain of St. aureus membranes. According to their relaxation parameters and redox properties, these iron-sulfur centers are similar to iron-sulfur centers S-1 and S-3 corresponding to succinate dehydrogenases of mitochondria and bacterial membranes.
The combined effect of ethonium, a synthetic surface active substance and preparations of lytic enzymes on staphylococcal cells and possible use of ethonium for preprocessing the staphylococcal biomass were studied. With addition of ethonium to the reaction system the activity of the enzyme preparations against both the intact staphylococcal cells and the preheated ones markedly increased. The maximum activity of the lytic enzymes was observed when the substance concentration was equal to 25 mg/l. Preprocessing of the biomass with 0.05% ethonium solution increased the rate and strength of the enzymatic lysis. The data are indicative of possible decrease of the concentration of the lytic enzymes and efficient usage of low active preparations in disintegration of staphylococcal cells in the presence of ethonium.
The lysoenzyme preparation from Streptomyces recifensis subsp. lyticus 2435 had a marked lytic activity against staphylococci of different species, spectra and antibiotic sensitivity. Certain strain differences of the cells in the population could be easily eliminated with increasing the dose. The preparation is a complex of lytic enzymes with high antimicrobial activity. It was concluded that it could be considered as a potentially promising chemotherapeutic agent for treatment of staphylococcal infections.
Ability of an enzyme complex from Streptomyces recifensis var. lyticus 2435 to inactivate beta-lactam antibiotics was shown. Two lytic endopeptidases with beta-lactamase activity were isolated and identified as beta-lactamases of classes II and V according to the Richmond and Sykes classification system. The ability of the endopeptidases to hydrolyze the beta-lactam ring confirmed the absence of strict substrate specificity in them. Correlation between the capacity of the lytic endopeptidases for lysing staphylococcal cells and their capacity for inactivating beta-lactam antibiotics was observed.
Dependence of lytic enzyme preparation activity on temperature and time of Staphylococcus incubation with the preparation was shown. A decrease in the activity with an increase in the ionic strength of the incubation solutions and protective effect of salts on the staphylococcal cells were observed. Possible combined use of the preparation with antibiotics was studied. The enzymatic preparation inactivated penicillins and cephalosporins at the account of the ability of lytic endopeptidases to hydrolyze the peptide bond of the beta-lactam ring. However, its combined use with many other antibiotics such as novobiocin, lincomycin, rifampicin, gramicidin, polymyxin, oleandomycin, streptomycin, kanamycin, tetracycline and levomycetin is quite possible.
The properties of the membrane respiration apparatus of three clinical staphylococcal strains and their novobiocin resistant variants were studied comparatively. Changes in the specific activity of the respiration enzymes were shown: when the dehydrogenase activity of the membrane preparations of the sensitive and resistant variants was equal and the specific quantity of cytochromes in the novobiocin resistant staphylococci was lower, the oxidase activity of their respiration chains was increased by 60-70 per cent. Disintegration of the cells of the novobiocin resistant staphylococci resulted in a higher yield of the membrane protein, the membrane fraction being characterized by a activity of phospholipase A.
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