Role of aspartic acid 38 in the cofactor specificity of Drosophila alcohol dehydrogenase.

Journal Article

Drosophila alcohol dehydrogenase (ADH), an NAD(+)-dependent dehydrogenase, shares little sequence similarity with horse liver ADH. However, these two enzymes do have substantial similarity in their secondary structure at the NAD(+)-binding domain [Benyajati, C., Place, A. P., Powers, D. A. & Sofer, W. (1981) Proc. Natl Acad. Sci. USA 78, 2717-2721]. Asp38, a conserved residue between Drosophila and horse liver ADH, appears to interact with the hydroxyl groups of the ribose moiety in the AMP portion of NAD+. A secondary-structure comparison between the nucleotide-binding domain of NAD(+)-dependent enzymes and that of NADP(+)-dependent enzymes also suggests that Asp38 could play an important role in cofactor specificity. Mutating Asp38 of Drosophila ADH into Asn38 decreases Km(app)NADP 62-fold and increases kcat/Km(app)NADP 590-fold at pH 9.8, when compared with wild-type ADH. These results suggest that Asp38 is in the NAD(+)-binding domain and its substituent, Asn38, allows Drosophila ADH to use both NAD+ and NADP+ as its cofactor. The observations from the experiments of thermal denaturation and kinetic measurement with pH also confirm that the repulsion between the negative charges of Asp38 and 2'-phosphate of NADP+ is the major energy barrier for NADP+ to serve as a cofactor for Drosophila ADH.

Full Text

Duke Authors

Cited Authors

  • Chen, Z; Lee, WR; Chang, SH

Published Date

  • December 1991

Published In

Volume / Issue

  • 202 / 2

Start / End Page

  • 263 - 267

PubMed ID

  • 1761031

Pubmed Central ID

  • 1761031

Electronic International Standard Serial Number (EISSN)

  • 1432-1033

International Standard Serial Number (ISSN)

  • 0014-2956

Digital Object Identifier (DOI)

  • 10.1111/j.1432-1033.1991.tb16371.x

Language

  • eng