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Biomedical subjects

A I Severin

Publications and source records attributed to A I Severin.

6 recordsLinked to original sources
PubMed1978

Metabolic and genetic control of isoenzyme spectrum of alkaline phosphatase in Escherichia coli.

Three proteins possessing alkaline phosphatase activity were detected in a fraction of periplasmic material of Escherichia coli K-10 and its mutants with constitutive synthesis of alkaline phosphatase. They also showed acid phosphatase, pyrophosphatase and ATPase activities. Through the use of phosphatase-negative mutants it was shown that these proteins were the products of a single structural gene and therefore represented alkaline phosphatase isozymes. The numbers of enzyme isoforms and possibly the spectrum of their phosphohydrolase activities were controlled by exogenous orthophosphate and depended on the integrity of regulator genes for alkaline phosphatase.

Acid Phosphatase↗
PubMed1976

[Escherichia coli membrane-bound polyphosphatase].

A complex of polyphosphatase with E. coli membranes has been isolated and studied. It is shown by gel-filtration through G-200 Sephadex and centrifugation in sucrose concentration gradient that about 5% of polyphosphatase total content in cells is bound with the heterogenous fraction containing smooth membranes and the ribosome-membrane complex. On the basis of the data obtained it is suggested that the formation of a complex of polyphosphatase with membranes is a stage of synthesis and secretion of this enzyme to protoplasm.

Escherichia coli↗
PubMed1976

[Effect of detergents and proteolytic enzymes on membrane-bound phosphohydrolases in Escherichia coli cells with repressed and depressed biosynthesis of these enzymes].

Solubilization of protein membranes by detergents and protein liberation from the membranes induced by proteolytic enzymes results in a change of activity of membrane-bound phosphohydrolases--alkaline phosphatase and polyphosphatase. The activity of enzymes under conditions of repressed and derepressed biosynthesis of phosphohydrolases changes differently, thus indicating their different membrane environment in the two types of membranes. Some data were obtained on the localization of alkaline phosphatase in a hydrophobic region, possibly in lipid bilayer and polyphosphatase in the surface layers of the membrane.

Binding Sites↗
PubMedDate not supplied

[Enzymes of a bacteriolytic lysoamidase preparation. Various properties of bacteriolytic protease L2].

Bacteriolytic proteinase L2 is able to cleave fluorogenic synthetic tripeptide anthranoyl-alanyl-alanyl-phenylalanyl-nitroanilide (Abz-Ala-Ala-Phe-pNA) at the bond between phenylalanine and p-nitroaniline. Optimal conditions of the tripeptide cleavage have been determined: pH 6.7 + 0.1; mu = 2 (by NaCl); t = 40 degrees C; KM = 2.6 x 10(-5) M. Metal cations reduced the enzyme activity. The enzyme was inhibited by EDTA, p-CMB, DIF. The synthetic tripeptide can be used to determine the activity of the L2 enzyme.

Amino Acid Sequence↗
PubMedDate not supplied

[Protein content of E. coli membrane under conditions of repressed and derepressed biosynthesis of alkaline phosphatase].

Protein content of membranes in wild type strains of E. coli K12 and K10 and in mutants defective in alkaline phosphatase regulator genes: E. coli C85 (R1-R2+p+) and E. coli C4(R1+R2-P+) under the conditions of repression and derepression of this enzyme was studied. Correlation between the content in membranes of minor component with the molecular weight 30,700 and the state of the regulatory system of alkaline phosphatase biosynthesis was shown. This protein was absent in the membranes of the repressed cells of wild type strains and in the membranes of nonrepressible (constitutive) mutant E. coli C4. Probably the protein with molecular weight 30,700 is a product of the regulatory gene R2 and its binding with the membrane determines its regulatory function.

Alkaline Phosphatase↗