Occurrence of a large molecular size form of polyphosphate-glucose phosphotransferase in extracts of Mycobacterium tuberculosis H37Ra.

Extracts prepared by sonicating Mycobacterium tuberculosis H37Ra cells with subsequent centrifugation at 18,000 X g proved to contain a very large molecular size form of polyphosphate-glucose phosphotransferase. The enzyme was separable by polyacrylamide gel electrophoresis, DEAE-cellulose chromatography or ultracentrifugation. When rechromatographed at alkaline pH values, it gave rise to one of the soluble forms of lower molecular weight. The conversion also took place as a result of n-butanol extraction or salting out with ammonium sulfate and heating of dissolved pellet. Under certain conditions the lower-molecular weight enzyme converted to the higher-molecular weight form by association with a hitherto undefined cell constituent. It is assumed that both ionic and hydrophobic forces play a role in this interconversion phenomenon.

Separation and properties of polyhydric alcohol dehydrogenases from Mycobacterium sp. 279 and Mycobacterium phlei.

Glucose- or polyol-grown mycobacteria were disrupted by ultrasonication and cell-free extracts fractionated with ammonium sulfate, Sephadex G-100 and DEAE-cellulose chromatography. In various enzyme preparations, NAD-coupled polyol dehydrogenase activities were determined spectrophotometrically at 340 nm. Evidence is presented forthe occurrence of three types of enzymes called after the most active substrates: ribitol dehydrogenase, D-arabitol dehydrogenase and D-sorbitol dehydrogenase. The enzymes have been separated, and characterized on the basis of their polyol specificity, molecular weight, heat resistance and pH stability. The dehydrogenation reaction was influenced by the kind of buffer and proceeded most rapidly with glycine/NaOH in a range of pH from about 9 (for glycerol, erythritol, and ribitol) to about 11 (for other polyols). Tris buffer was found to inhibit the reaction with polyhydric alcohols containing D-ribo or D-xylo configuration. Km values for several polyols and Ki for Tris have been established.

A mannoglucokinese of Mycobacterium tuberculosis H37Ra.

An ATP: D-glucose and D-mannose 6-phosphotransferase activity was found in Mycobacterium tuberculosis HERa. The activity was separated from other ATP- and polyphosphate D-glucose phosphotransferases in a procedure involving precipitation with ammonium sulfate, treatment with calcium phosphate gel, DEAE-cellulose and DEAE-Sephadex A50 chromatography. The optimum pH of the phosphorylation reaction was from 9 to 10.5. The hexokinase phosphorylated D-glucose with a Km of 20 mM under conditions of MgATP saturation. The Km for MgATP was 0.2 mM. The enzyme showed a higher activity on D-mannose at a saturation level being about 100-fold lower than that of D-glucose; it did not utilize either D-fructose or D-glucosamine. Inorganic poly(P) could not replace ATP as the phosphate donor. M. tuberculosis H37Ra was unable to grow on D-mannose which may suggest that the enzyme studied is involved in endogenous metabolism of this sugar.

Polyphosphate-glucose phosphotransferase. Purification of Mycobacterium tuberculosis H37Ra enzyme to apparent homogeneity.

1. The enzyme (EC 2.7.1.63) was isolated from glucose-grown M. tuberculosis H37Ra; during the purification procedure, 2-mercaptoethanol, glucose, EDTA and NaCl served as protecting agents. 2. The enzyme was purified about 600-fold. The preparation was homogeneous on polyacrylamide-gel electrophoresis and gave one precipitin line in double immunodiffusion test. Molecular weight of the enzyme determined by Sephadex G-100 filtration was about 118 000. 3. The enzyme preparation showed also glucokinase activity with ATP.

Purification and properties of L-asparaginase from Mycobacterium phlei.

1. L-asparaginase from M. phlei was purified about 170-fold with an 11% yield. The purification procedure consisted of: fractionation with ammonium sulphate; adsorption of contaminating proteins on calcium phosphate gel; chromatography on Sephadex G-150 and DEAE-cellulose. The specific activity of the final preparation was 32.6 i.u./mg protein. 2. Molecular weight of the enzyme as determined by Sephadex G-100 filtration amounted to 126 000. Optimum pH was 8.8-9.2. The enzyme did not hydrolyse L-glutamine over the pH range 4-9, and was inhibited by D-asparagine. The apparent Michaelis constant for L-asparagine was 0.7 mM; energy of activation, 9800 cal/mole. 3. On polyacrylamide-gel electrophoresis the final preparation revealed two protein bands, one of which was coincident with the enzyme activity.

L-asparaginase activity of Mycobacterium phlei under various growth conditions.

Seven Mycobacterium strains were grown statically on salts-glycerol-asparagine (Sauton) or on salts-glucose-glutamate (Sym) media. At desired time of incubation, the bacteria were washed with water, disintegrated with powdered corundum and in resulting cell-free extracts L-asparaginase activity was determined by the Conway method. The majority of experiments were performed on M. phlei which exhibited considerable rise in L-asparaginase activity with increasing age of the culture. This change did not occur on Sym medium because of Zn2+, which proved to abolish the effect of the enzyme induction in vivo but did not inhibit the activity in vitro. Addition of rifampicin to Sauton culture media resulted in a low enzyme level. Exogenous asparagine and glycerol were not indispensable for the enzyme synthesis and could be replaced by glutamate and glucose, respectively.