L-asparaginase activity in cell-free extracts of Thermoactinomyces vulgaris 13 M.E.S.

Crude extracts of Thermoactinomyces vulgaris 13 M.E.S. were prepared by different procedures and their L-asparaginase activity was compared. The optimum conditions for the enzyme activity in the crude extract was exerted at pH 8.8, using borate or tris-HCl buffer, or at pH 7.4, using phosphate buffer, after a reaction time of 30 minutes at 50-55 degrees C, using 1.35-5.4 mg protein of the crude extract. The enzyme showed an apparent km value of 4.5 x 10(-3), was more thermostable in crude extracts than in whole cells, and was inhibited by HgCl2, KCN, DL-asparagine, L-aspartic acid, and ammonium hydroxide. Enzyme purification by alcohol precipitation and gel filtration was attempted.