| Abstract: | Long-chained 1-mercapto-n-alkanes showed potent inhibitory effects on horse liver alcohol dehydrogenase (HLADH). The inhibitory effect of the thiols was enhanced by increasing the number of the alkyl carbon atoms up to 10-12 and steeply lowered by further increase in the carbon number. The HLADH activity was almost completely inhibited in competitive manner by an equivalent concentration of 1-mercapto-n-decane or -n-dodecane to that of the subunit of the dimeric zinc enzyme; inhibition constant Ki was 0.55 nM for the former. The present study strongly suggests that the thiols interact simultaneously with at least two sites of HLADH; the primary one could be the zinc atom in the active site of the enzyme, interacting with the sulfhydryl groups, and the other a hydrophobic binding site for the their alkyl carbons. |
