Coupling between 3-ketosteroid-delta'-dehydrogenase and the respiratory chain in the bacterium Arthrobacter globiformis

Intact bacterial cells and their cytoplasmic membranes obtained by ultrasonic desintegration are able to induce dehydration of hydrocortisone to prednisolone that is coupled with O2 uptake. This reaction is inhibited by cyanide and 2-n-nonyl-4-hydroxyquinoline-N-oxide (HOQNO). Oxidation of hydrocortisone results in cytochrome reduction both in intact cells and in cytoplasmic membranes. Aerobic dehydration of hydrocortisone is linked with transmembrane potential generation. The data obtained suggest that the electron translocation from 3-ketosteroid-delta'-dehydrogenase to O2 occurs via the respiratory chain. The enzyme donates reduced equivalents directly to the respiratory chain, presumably at the level of menaquinone.     

Isolation and characterization of a new low-molecular antibacterial peptide of the lantibiotics family

The physicochemical and biological properties of the low-molecular antibacterial peptide isolated from the cultivation medium of Staphylococcus warneri IEGM KL-1 were studied. The peptide was obtained in a homogenous state by the methods of ultrafiltration, ion exchange, and reversed phase chromatography. The peptide contained a substantial quantity of cationic and hydrophobic amino acid residues and an uncommon amino acid lanthionine. The molecular mass of the peptide was 2999 Da. A bactericidal effect of the isolated peptide on the cells of S. epidermidis 33 was exhibited in a wide pH range, being completely preserved upon heat treatment. In accordance with the characteristics, origin, and species affiliation of the producer, the peptide was named warnerin. The available data allow us to consider warnerin as a new representative of the family of lantibiotics, promising antibiotic agents of microbial origin.     

Production of Candida lipolytica protoplasts]

Optimal conditions were found for the production and isolation of the protoplasts of Candida lipolytica. The maximum amount of the protoplasts was produced after 90 minutes of the incubation with a crude preparation of the enzyme from Helix pomatia (100 mg/g wet biomass). Longer incubation results in lysis of the protoplasts and structural damages of the intracellular components. The yield of the protoplasts does not depend on the nature of stabilizing agent. A decrease in the stabilizer concentration increases the yield of the protoplasts four times. Preliminary treatment of the yeast cells with a 0.1 M solution of SH compounds (cysteine, beta-mercaptoethanol) does not increase the yield of the protoplasts; and 0.2 M solution of these compounds decreased the yield of the protoplasts.     

Effect of the artificial electron acceptor reumycin on the nature of an intermediate accumulated by Pseudomonas aeruginosa bacteria

We investigated the effect of the autooxidizable electron acceptor reumicin on the oversynthesis of intermediates by the bacterium Pseudomonas aeruginosa during its growth limitation by a nitrogen source. Addition of reumicin which accepted the reducing equivalents from NADH(+)-dehydrogenase of the respiratory chain was shown to reduce the rate of alpha-ketoglutarate formation and yield, and to induce the synthesis and excretion of pyruvate into the cultivation medium. The maximal accumulation of pyruvate was observed when reumicin was added at a concentration of 0.4-0.5 mM. It is concluded that the nature of the overproduced intermediate, the rate of its biosynthesis and yield depend on the extent of reducibility of the pyridine nucleotide pool. The oversynthesis of alpha-ketoglutarate is suppressed by chloramphenicol, a protein synthesis inhibitor, which points to a possible involvement of inducible systems including the carriers of the acids via the cytoplasmic membrane.     

Coordinate embryonic expression of three zebrafish engrailed genes.

We have identified three genes, expressed in zebrafish embryos, that are members of the engrailed gene family. On the basis of sequence comparisons and analyses of their expression patterns, we suggest that two of these genes, eng2 and eng3, are closely related to the En-2 gene of other vertebrates. The third gene, eng1, is probably the zebrafish homolog of En-1. Subsets of cells at the developing junction between the midbrain and hindbrain express three different combinations of these genes, revealing a previously unknown complexity of this region of the CNS. Other cells, for example, jaw and myotomal muscle precursors, express two of the three genes in combinations which, in the myotomal muscles, change during development. Cells in the developing hindbrain and fins express only a single engrailed gene. We propose that the fates and patterning of these cells may be regulated by the coordinate expression of particular combinations of these closely related homeoproteins.     

High performance liquid chromatography and characterization of structural proteins of the influenza virus

Constituent proteins of human influenza virus A have been separated by reverse-phase HPLC on Polysil ODS-500. Their homogeneity is confirmed by the data of amino acid composition, Edman analysis and gel electrophoresis.     

Glucose metabolism in Clostridium sporogenes and Clostridium sticklandii bacteria

Clostridium sporogenes 272 has a high rate of glucose fermentation. Its cell-free extract contains all glycolytic enzymes catalysing glucose degradation to pyruvate and shows the phosphoroclastic activity. C. sticklandii CSG has a low rate of glucose fermentation. Hence, the activity of the following enzymes is lower in this organism comparing to C. sporogenes: phosphohexoisomerase (EC 5.3.1.9), phosphofructokinase (EC 2.7.1.11), aldolase (EC 4.1.2.13), triosephosphate isomerase (EC 5.3.1.1) and glyceraldehyde phosphate dehydrogenase (EC 1.2.1.12). Moreover, it is possible that the system of glucose transport into the cell is damaged in C. sticklandii.