[Dependence of extracellular proteases synthesis on the growth phase of Pseudomonas fluorescens]. / Zavisimost' sinteza vnekletochnykh proteaz ot fazy rosta u Pseudomonas fluorescens.

The aim of this work was to study the dependence of the synthesis of exocellular proteolytic enzymes on the growth phase of Pseudomonas fluorescens which was cultivated in media containing amino acids as a sole carbon source. In all of the studied cases, the proteolytic activity of the medium increased in parallel to the bacterial growth until the culture reached the stationary growth phase. Chloramphenicol added in the phase of intensive growth ceased the increase of the proteolytic activity of the medium without a noticeable delay in time. This fact indicates that the processes of translation and secretion of exoproteases occur virtually at the same time in the cell of P. fluorescens. The rate of degradation of exocellular proteolytic enzymes was shown to be insignificant in comparison to the rate of their synthesis. Therefore, the increase in the proteolytic activity of the medium directly reflects the rate of synthesis of exoproteases.

[Localization of metabolites which are regulators of extracellular protease synthesis in Pseudomonas fluorescens bacteria]. / O lokalizatsii metabolitov--reguliatorov sinteza vnekletochnykh proteaz u bakterii Pseudomonas fluorescens.

The effect of over forty low molecular weight substrates on the growth and synthesis of exocellular neutral proteases was studied in Pseudomonas fluorescens. Neutral exoproteases were found to be regulated enzymes. Glucose did not repress the synthesis of exocellular proteases; the regulation of their synthesis by amino acids involved the mechanism of induction. The data suggest that the primary intracellular inductors of the synthesis of exoproteases are formed for different groups of amino acids at different levels of their utilization by the cells, viz. at the level of transport and at the level of the first steps in the degradation of their carbon backbones. The paper discusses possible molecular mechanisms for integrating the signal of the primary intracellular inductors, which directly regulate the activity of the operon(s) of neutral exocellular proteases.

[Synthesis of D-ribulose-1,5-diphosphate with immobilized enzymes of Thiobacillus]. / Sintez D-ribulozo-1,5-difosfata immobilizovannoi fermentnoi sistemoi tionovykh bakterii.

Preparative synthesis of D-ribulose-1,5-diphosphate (RuDP) from ribose-5-phosphate and ATP was carried out, using as a catalyst a crude extract of Thiobacillus thiooxidans 58 R immobilized on porous glass. The methods for immobiliztion of crude bacterial extracts, synthesis of RuDP and purification of the resultant product by means of column chromatography on activated charcoal and anionites were developed. The structure of RuDP was identified by 13C-NMR spectroscopy. Stability of two phosphate groups of RuDP during acid and alkaline hydrolysis proved to be different: both phosphate groups were completely removed in 1 N H2SO4 at 100 degrees C whereas only one phosphate group was hydrolysed in 1 N NaOH at 25 degrees C. This finding is at variance with the earlier results of Horecker et al. (1956).