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.