The metabolism of leukotrienes in blood plasma studied by high-performance liquid chromatography

The metabolism of leukotrienes (B4, C4, D4, and E4) within human plasma was studied and a simple sample preparation is presented. It was demonstrated that leukotriene E4 and leukotriene B4 were stable during incubation at 37 degrees C using the in vitro system. In contrast, leukotriene C4 was metabolized by gamma-glutamyl transpeptidase activities into leukotriene D4 which was further metabolized by dipeptidase activities of plasma into leukotriene E4. The transition state inhibitor of gamma-glutamyl transpeptidase L-serine-borate decreased the metabolism of leukotriene C4 in plasma. Dilution of plasma demonstrated that the dipeptidase was more active compared to the gamma-glutamyl transpeptidase. The metabolizing activities of plasma were functionally characterized by fractionating the plasma proteins.     

The diagnosis of antileptospiral antibodies in human subjects by solid-phase immunoenzyme analysis

The possibility of using the enzyme-linked immunosorbent assay (ELISA) for the diagnosis of leptospirosis has been shown. This method has proved to be more simple and sensitive than the leptospiral microagglutination and lysis test. The data on obtaining genus-specific leptospiral antigens are presented. As revealed in this study, the antigens obtained by the complex treatment of microbial cells with ultrasound and detergents show the maximum activity in ELISA. The optimum parameters of the ELISA system for the diagnosis of leptospirosis have been established.     

The role of fibronectin in the streptococcal adhesion process

The work shows that fibronectin obtained from human plasma is capable of binding with streptococci of different groups with almost equal effectiveness. Fibronectin bound to bacterial cells inhibits the adhesion of group A streptococci onto vaginal cells, but it produces no effect on the adhesion of group B streptococci. The binding constant of fibronectin 125I is equal to 10(6) -M-1, which indicates that the level of the specificity of interaction is not sufficiently high.     

New indications for the participation of group P plasmids R in the transfer of chromosomal genes in intergenera crosses]

Use of E. coli strains with phenotypes Rec+ and Rec- asrecipients in intergenera crosses confirmed the supposition put forward by the authors formerly that new chromosomal markers in transconjugantes originated due to Psuedomonas aeruginosa. These chromosomal markers were transferred together with plasmid R conditioning the conjugation, and maintained without being built-into E. coli chromosome. Between the arg+ marker and the plasmid R18 there existed labile physical connection demonstrable only under definite conditions of recombinant selection.     

Enzyme catalyzed hydrolysis of inorganic pyrophosphate. Current view of problems in characterization of PP1-phosphohydrolytic activity associated with alkaline phosphatases (EC 3.1.3.1).

A survey of the hydrolytic activity of alkaline phosphatase (EC 3.1.3.1) reveals that PP1, like phosphomonoesters, can serve as substrate in vitro. This pp1-phosphohydrolytic activity can be distinguished from PP1-phosphohydrolytic activities of inorganic pyrophosphatases (EC 3.6.1.1) and glucose-6-phosphatase (EC 3.1.3.9) by several criteria. Discrimination among these hydrolytic enzymes is possible by their dependence on variation of pH and of magnesium to PP1 ratios in the assay solutions. The true substrates and modifiers are not simply PP1 and magnesium, but the equilibrium species in mixtures of these two. The physiological significance of each of the three enzymes is not predictable from their differential efficiency as catalysts of PP1-hydrolysis in vitro.     

Dehalogenation of 4-chlorobenzoate by 4-chlorobenzoate dehalogenase from pseudomonas sp. CBS3: an ATP/coenzyme A dependent reaction

Pseudomonas sp. CBS3 was grown with 4-chlorobenzoate as sole source of carbon and energy. Freshly prepared cell-free extracts converted 4-chlorobenzoate to 4-hydroxybenzoate. After storage for 16 hours at 25 degrees C only about 50% of the initial activity was left. Treatment at 55 degrees C for 10 minutes, dialysis or desalting of the extracts by gel filtration caused a total loss of the activity of the 4-chlorobenzoate dehalogenase. The activity could be restored by the addition of ATP, coenzyme A and Mg2+. If one of these cofactors was missing, no dehalogenating activity was detectable. The amount of 4-hydroxybenzoate formed was proportional to the amount of ATP available in the test system whereas CoA served as a real coenzyme. A novel ATP/coenzyme A dependent reaction mechanism for the dehalogenation of 4-chlorobenzoate by 4-chlorobenzoate dehalogenase from Pseudomonas sp. CBS3 is proposed.