title: Sequential protection-modification method for selective sulfhydryl group derivatization in proteins having more than one cysteine.
abstract: The method of Smith and Hartman [J. Biol. Chem., 263, 4921-4925 (1988)] for introducing the non-natural lysine analog, S-(2-aminoethyl)cysteine, into specific sites in proteins by alkylation of a genetically introduced cysteine with 2-bromoethylamine has been generalized to be applicable to proteins containing one or more endogenous cysteines. The target cysteine residue introduced at the active site of aspartate aminotransferase is protected by bound cofactor. The enzyme is partially unfolded in low concentrations of urea, and the non-active site cysteine residues derivatized by a reversible thiol protecting reagent. The active site cysteine is then exposed and alkylated in 6 M urea. Enzyme activity is regenerated by removal of the thiol protecting groups and refolding of the protein.
authors.affiliation: Department of Molecular and Cellular Biology, University of California, Berkeley 94720.
authors.forename: A
authors.initials: A
authors.lastname: Planas
authors.forename: J F
authors.initials: JF
authors.lastname: Kirsch
mesh_terms: D000477:Alkylating Agents; D001221:Aspartate Carbamoyltransferase / Q000235:genetics; D055598:Chemical Phenomena; D002621:Chemistry; D003545:Cysteine / Q000032:analysis; D007700:Kinetics; D009154:Mutation; D011487:Protein Conformation; D011489:Protein Denaturation; D015202:Protein Engineering; D013438:Sulfhydryl Compounds / Q000032:analysis
chemical_list: D000477:Alkylating Agents; D013438:Sulfhydryl Compounds; D001221:Aspartate Carbamoyltransferase; D003545:Cysteine