Cations in component reactions of `malic' enzyme catalysis |
| |
| Authors: | C S Tsai Y H Tsai and R A Samad |
| |
| Institution: | Department of Chemistry, Carleton University, Ottawa, Ont., Canada |
| |
| Abstract: | The ;malic' enzyme (EC 1.1.1.40) has been purified (300-fold) from wheat germ and its abilities to catalyse the decarboxylation and the hydrogenation of oxaloacetic acid and oxaloacetate esters was studied. The free 1-carboxyl group is essential for the interaction of oxaloacetates and substituted oxaloacetates with the enzyme via cations. The free 4-carboxyl group is required for the decarboxylation but is not indispensable for the hydrogenation. At high concentrations, cations inhibit the enzymic hydrogenation of oxaloacetic acid but not that of 4-ethyl oxaloacetate. A plausible inhibitory mechanism is proposed. |
| |
| Keywords: | |
|
|
