title: Introduction of sulfhydryl groups into proteins at carboxyl sites.
abstract: A two-step procedure for introduction of sulfhydryl groups at protein carboxyl groups is described. The resultant proteins contain 2-aminoethanethiol residues bound by amide linkages to the protein carboxyl groups. First an amide bond is formed between a carboxyl group of the protein and one of the amino groups of cystamine. Then the disulfide bond is reduced with dithiothreitol, yielding the amide of 2-aminoethanethiol. This procedure was used to incorporate sulfhydryl groups into carbonic anhydrase and adrenocorticotropic hormone. The effect of carbodiimide concentration and pH of the coupling reaction on stoichiometry of sulfhydryl group incorporation was examined. The method was used to prepare bovine carbonic anhydrase containing up to nine sulfhydryl groups per molecule with no loss of enzymatic activity and biologically active adrenocorticotropic hormone containing one sulfhydryl group per molecule.
authors.affiliation: Department of Biochemistry, University of Nebraska-Lincoln 68583-0718.
authors.forename: C M
authors.initials: CM
authors.lastname: Lin
authors.forename: K A
authors.initials: KA
authors.lastname: Mihal
authors.forename: R J
authors.initials: RJ
authors.lastname: Krueger
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000378:metabolism*; D000818:Animals; D002256:Carbonic Anhydrases / Q000378:metabolism*; D002417:Cattle; D055598:Chemical Phenomena; D002621:Chemistry; D003538:Cystamine / Q000378:metabolism; D004950:Esterases / Q000378:metabolism; D005022:Ethyldimethylaminopropyl Carbodiimide / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D013438:Sulfhydryl Compounds / Q000378:metabolism*
chemical_list: D013438:Sulfhydryl Compounds; D000324:Adrenocorticotropic Hormone; D004950:Esterases; D002256:Carbonic Anhydrases; D003538:Cystamine; D005022:Ethyldimethylaminopropyl Carbodiimide