L-Serine dehydratase in some filamentous fungi II- comparative properties of L-Serine dehydratase of cunninghamella elegans and fusarium oxysporum

ABSTRACT

L-Serine dehydratase [EC 4.21.13] of Cunninghamella elegans and Fusarium oxysporum had a pH optimum of 8. Maximal activity of L- serine dehydratase of C. elegans occurred at 50C, while that of F. oxysporum enzyme was optimal at 40-50C. Both enzymes were thermolabile Km of C. elegans enzyme for L-Serine was 20 mM, whereas that of F. Oxysporum enzyme was 30 mM. The two enzymes were highly specific for L-Serine. The catalytic activity of both enzymes was inhibited by Zn2+, Cu2, Co2+, Mn2+ and Ca2+. No cofactor requirement was observed for both enzymes. L-Cysteine inhibited C. elegans enzyme competitively with a Ki of 0.87 mM and that of F. Oxysporum enzyme noncompetitively with a Ki of 3.81 mM