Site-directed mutagenesis of the alpha subunit of tryptophan synthase from Salmonella typhimurium.


Abstract

Site-specific mutagenesis has been used to prepare two mutant forms of the alpha subunit of tryptophan synthase from Salmonella typhimurium in which either cysteine-81 or cysteine-118 is replaced by a serine residue. These mutant proteins are potentially useful for x-ray crystallographic studies since a heavy metal binding site is specifically eliminated in each mutant. The purified mutant proteins are fully active in four reactions catalyzed by the wild type alpha 2 beta 2 complex of tryptophan synthase. However, the mutant alpha 2 beta 2 complexes dissociate more readily and are less heat-stable than the wild type alpha 2 beta 2 complex. Thus, cysteine-81 and cysteine-118 of the alpha subunit serve structural but not functional roles. Study holds ProTherm entries: 102, 103, 104 Extra Details: 2-mercaptoethanol (10 mM) and EDTA(1 mM) are added as additives. alpha subunit of tryptophan synthase; site-specific mutagenesis;,structural role; heavy metal binding site

Submission Details

ID: fVMDGtY23

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:14 p.m.

Version: 1

Publication Details
Ahmed SA;Kawasaki H;Bauerle R;Morita H;Miles EW,Biochem. Biophys. Res. Commun. (1988) Site-directed mutagenesis of the alpha subunit of tryptophan synthase from Salmonella typhimurium. PMID:3126743
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