Site-specific mutagenesis of Drosophila alcohol dehydrogenase: evidence for involvement of tyrosine-152 and lysine-156 in catalysis.

Journal Article (Journal Article)

Amino acid sequence comparisons reveal that tyrosine-152 and lysine-156 of Drosophila alcohol dehydrogenase (ADH) are conserved in homologous dehydrogenases, suggesting that these residues are important in catalysis. To test this hypothesis, we used site-directed mutagenesis to substitute tyrosine-152 with phenylalanine, histidine, or glutamic acid or to substitute lysine-156 with isoleucine. All of these mutants are catalytically inactive. Two mutants were active: A cysteine mutation of tyrosine-152 has 0.25% of wild-type ADH activity, while an arginine substitution of lysine-156 retains 2.2% of wild-type ADH activity. Kinetic analysis shows that the cysteine mutant increases Km(ethanol) 56-fold and Km(propan-2-ol) 100-fold, while Km(NAD) values are essentially unaltered. The arginine mutant also shows the significant enlargement of Km(ethanol), but not of Km(NAD). Furthermore, the cysteine mutant and arginine mutant have different substrate specificity and behave differently on competitive inhibition than wild-type ADH. These results suggest that both tyrosine-152 and lysine-156 have essential roles in catalysis by Drosophila ADH.

Full Text

Duke Authors

Cited Authors

  • Chen, Z; Jiang, JC; Lin, ZG; Lee, WR; Baker, ME; Chang, SH

Published Date

  • April 6, 1993

Published In

Volume / Issue

  • 32 / 13

Start / End Page

  • 3342 - 3346

PubMed ID

  • 8461298

International Standard Serial Number (ISSN)

  • 0006-2960

Digital Object Identifier (DOI)

  • 10.1021/bi00064a017

Language

  • eng

Conference Location

  • United States