Department of Biochemistry

Alcohol dehydrogenases are enzymes used in yeast for the production of ethanol by fermentation of glucose and by man for the metabolism of alcohols. The five human alcohol dehydrogenases differ in specificities for substrates; their roles in normal metabolism and the pathogenesis of alcoholism are yet to be discovered. We are using protein engineering, steady-state and transient kinetics, chemical modification and x-ray crystallography to investigate the structure and catalytic mechanism of the enzymes. The diagram below shows the active site of the horse liver enzyme, based on X-ray studies. Site-directed mutagenesis is being used to prepare variants of the liver and yeast enzymes for studies on the catalytic mechanism and conformational flexibility. The size of the substrate binding pocket is being varied in order to study determinants of specificity. The overall structure of the protein, the tertiary and quaternary arrangements, are being modified so as to make a minimal catalytic unit and to study the role of dynamics in catalysis. The variant enzymes are crystallized for the determination of the three-dimensional structures.