| Abstract: | Effect of some 3- and 4-substituted pyridines on enzymatic hydrolysis of NAD by rabbit heart muscle NAD-glycohydrolase has been studied. It is shown that some 4-substituted derivatives in contrast with 3-substituted ones produce an inhibitory effect on the enzyme activity. A new efficient inhibitor of rabbit heart muscle NAD-glycohydrolase (I50 = 10(-3) M)--N1-(2-lactyl)-N2-(isonicotinoy)hydrazine, inducing uncompetitive inhibition of hydrolysis of NAD is found. The mechanism of the inhibitory effect of N1-(2-lactyl)-N2-(isonicotinoyl)hydrazine was investigated and the rate equation for enzymatic hydrolysis of NAD in the presence of inhibitor is calculated. It is suggested, that the inhibitory effect of N1-(2-lactyl)-N2-(isonicotinoyl)hydrazine is due to the formation of triple inactive complex inhibitor-enzyme-adenosinediphosphateribose. |
