![]() The three-dimensional model shows that glycine-184 is close to the substrate binding site. Replacement of alanine-159 with threonine, which has a larger side chain and can hydrogen bond with water, is likely to reduce the strength of the hydrophobic interaction. It also shows that alanine-159 is part of a hydrophobic anchor on the dimer interface of ADH. The model indicates that mutations in glycine-17 and glycine-93 affect the binding of NAD+. The mutations were analysed in terms of a three-dimensional model of ADH using bacterial 20 beta-hydroxysteroid dehydrogenase and rat dihydropteridine reductase as templates. Interestingly, the Ala159Thr mutant does not form either stable homodimers or heterodimers with wild-type ADH, suggesting that alanine-159 is important in stabilizing ADH dimers. Although these mutants are inactive, three mutants (Gly17Arg, Gly93Glu and Gly184Asp) form stable homodimers, as well as heterodimers with wild-type ADH, in which the wild-type ADH subunit retains full enzyme activity. Four of these ADH mutants contain a single amino acid change: glycine-17 to arginine, glycine-93 to glutamic acid, alanine-159 to threonine, and glycine-184 to aspartic acid. We have determined the nucleotide sequences of eight ethyl methanesulphonate-induced mutants in Drosophila alcohol dehydrogenase (ADH), of which six were previously characterized by Hollocher and Place. Access content during the Covid-19 pandemic. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |