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

ABSTRACT

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