抄録
Treatment of yeast alcohol dehydrogenase [EC 1.1.1.1] (YADH) with dehydroascorbic acid (DHA) or D-arabinosone resulted in inactivation of the enzyme. Effects of other dicarbonyl compounds, such as D-glucosone and triosone, on YADH were also examined, and they were found to be less effective than D-arabinosone or ineffective.
The inactivation by DHA or D-arabinosone was accompanied by decrease of free sulfhydryl (SH) groups of the protein, and it was completely prevented by addition of SH compound. Treatment of the inactivated enzyme with β-mercaptoethanol led to partial reactivation with concomitant restoration of SH groups.
The inactivation of YADH was accelerated by NAD+ as well as NADH specifically.
These results strongly supported a possibility that DHA and D-arabinosone afforded the inhibitory effect on YADH through oxidation or modification of SH groups of the protein, which was favored in the presence of the coenzyme.
