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Abstract : |
Malic enzyme (ME, EC 1.1.1.40) from M. circinelloides and M. alpina were partially purified from crude extract, prepared from mycelia of both fungi after 16 h of growth, by ammonium sulphate precipitation and affinity column (Mimetic Green) to 24 and 22 fold purification, respectively. The enzyme from both fungi showed similar KM values for its cofactor,NADP, being 0.032 mM and 0.038 mM, respectively. A higher Km value for malate was observed for malic enzyme from M. alpina (1 mM) compared to that of M. circinelloides (0.4 mM). Inhibition studies were also carried out using tartronic acid, oxaloacetate, palmitoyl-CoA and oleoyl-CoA. At a concentration of up to 10 mM, tartronic acid caused a 40% inhibition of the activity of this enzyme for both fungi while oxaloacetate showed a higher degree of inhibition towards ME isolated from M. circinelloides ( 70%) compared to that of M. alpina (45%). Both oleoyl-CoA and palmitoyl-CoA exhibits a potent inhibitory effect (more than 90% inhibition) towards malic enzyme from both fungi but only at a level above the critical micellar concentration (3?m and 4 ?m, respectively)., |
