L-Alanine transaminase activities in some actinomycetes I- L- Alanine- glycine and L-alanine- glutamate transaminases of Streptomyces nitrosporeus

Cell-free extracts of some actinomycetes were found to contain some transaminases enzymes. Streptomyces nitrosporeus was selected as the most inducer for L-alanine-glycine and L-alanine glutamate transaminases. The first enzyme catalyzes the formation of pyruvate and lycine from L-alanine and glyoxylate, while the second enzyme catalyzes the formation of pyruvate and L-glutamate from L-alanine and alpha-ketoglutarate. The reversibility of the two reactions was demonstrated. The optimum activity of the first enzyme occurred at pH 7.5, while that of the second enzyme occurred at pH 8.0. The optimum temperature of the two enzymes was 40C. The temperature activity profiles and heat inactivation kinetics of the two enzymes were different, so the two reactions seem catalyzing by two different enzymes. The Km values for all substrate were calculated. The activity of the two enzymes was stimulated by the addition of pyridoxal phosphate, and was inhibited by the addition of hydroxylamine. The inhibition by hydroxylamine was overcome by pyridoxal phosphate. Stability of the two enzymes was studied. Dialysis for 24 hours against 0.02 M phosphate buffer pH 8.0, completely inhibited the activity of the two enzymes

Studies on the biosynthesis of L-aspartate 4-carboxy-lyase by Cunninghamella elegans and Penicillium citrinum

Cell-free extracts of Cunninghamella elegans and Penicillium citrinum contained L-aspartate 4-carboxylyase which catalyzes the beta- decarboxylation of L-aspartate to alpha-alanine and CO2. The enzyme was produced during the logarithmic phase of growth of the 2 organisms and maximum yield was obtained after 4 days incubation. The optimal pH range for L-aspartate 4-carboxylyase synthesis by C. elegans was 5 - 6, while for P. citrinum enzyme pH 5 was the optimal. L-aspartate 4-carboxylyase of both organisms was induced by L-aspartate and L- asparagine. L-aspartate concentration of 3.5 g/l was the optimal for L-aspartate 4-carboxylyase formation by both cultures. The effect of different carbon sources and metal salts on enzyme synthesis and growth of the two organisms was investigated

Comparative properties of crude L-aspartate 4-Carboxy-lyase of Cunninghamella elegans and Penicillium citrinum

The properties of L-aspartate 4-carboxylyase of Cunninghamella elegans and Penicillium citrinum were investigated. Both enzymes have a pH optimum of 5.5., maximal activity of both enzymes is obtained at 40 degrees and both are thermolabile. The Km of the C. elegans enzyme for L-aspartate is 25 mM, while that of the P. citrinum enzyme is 27 mM. The two enzymes are specific for L-aspartate. They are activated by pyridoxal 5-phosphate and a number of alpha-keto acids. The catalytic activity of both enzymes is stimulated by Co2+, Fe2+, Ni2 + and Mn2+ and inhibited by Zn2+ and Cu2+. The inhibition by iodoacetate and activation by SH-compounds suggests that sulfhydryl groups may participate in enzyme activity. Stability of the two enzymes on storage was investigated