Accession Number : ADA175459
Title : Uncompetitive Inhibition of Yeast Alcohol Dehydrogenase by Diacetoxyscirpenol.
Descriptive Note : Technical rept. Dec 84-Apr 85,
Corporate Author : CHEMICAL RESEARCH DEVELOPMENT AND ENGINEERING CENTER ABERDEEN PROVING GROUND MD
Personal Author(s) : Yeh,Homer R
Report Date : Oct 1986
Pagination or Media Count : 15
Abstract : A yeast alcohol dehydrogenase (YADH)-fusarium X complex was reported to have a molecular ratio of 1:4. The kinetics of the inhibitory effects of diacetoxyscirpenol (ADS) on YADH are presented here. Our kinetic data indicate that, at fixed levels of ADS, a series of parallel Lineweaver-Burk plots were obtained as concentrations of either ethanol or NAD varied. In the presence of .0021 M of ADS there was approximately a 6-fold decrease in K sub m, EtOH and V sub max values. The respective K sub m, EtOH and V sub max values decreased about 15- to 13-fold when ADS levels were increased to .0053 M. In the presence of .0021 M of the inhibitor, K sub m, NAD and the corresponding V sub max values decreased 2- to 3-fold, respectively, while in the presence of .0053 M of ADS, the corresponding kinetic constants reduced about 5-fold. These results indicate that ADS is either an uncompetitive or a mixed-type inhibitor with respect to either ethanol or NAD. However, replots of 1/V sub max and 1/K sub m, app versus inhibitor concentrations gave linear curves, which indicates a pure competitive inhibition with respect to both ethanol and NAD. As estimated from the replots, K sub i, EtOH and K sub i, NAD values of ADS were found to be in the range of .00004 M and .0018 M, respectively. The results suggest the formation of dead-end complexes of E-I-substrate and E-I-cofactor.
Descriptors : *PHYTOTOXINS , *ENZYME INHIBITORS , *DEHYDROGENASES , CONSTANTS , LINEARITY , YEASTS , KINETICS , INHIBITION , ALCOHOLS , CURVES(GEOMETRY) , FUSARIUM
Subject Categories : Toxicology
Distribution Statement : APPROVED FOR PUBLIC RELEASE