title: Completion of the amino acid sequence of papain.
abstract: Papain was inhibited with bromo[2-(14)C]acetic acid, the tertiary structure of the inhibited enzyme was unfolded and the disulphide bridges were reduced with mercaptoethanol and aminoethylated. Digestion with trypsin gave a radioactive peptide consisting of residues 18-58 inclusive and containing therefore the sequence of the thirteen unknown residues 29-41 in the primary sequence of papain. This peptide was digested with pepsin to give a radioactive peptide consisting of residues 18-47, which after digestion with 0.4m-hydrochloric acid gave a radioactive peptide consisting of residues 24-43 inclusive. Further digestion with 6m-hydrochloric acid gave peptides that were used to determine the sequence: Ser-Ala-Val-Val-Thr-Ile-Glx-Gly-Ile-Ile-Lys-Ile-Arg for the residues 29-41, so completing the amino acid sequence of papain.
mesh_terms: D000085:Acetates / Q000494:pharmacology; D000595:Amino Acid Sequence; D002247:Carbon Isotopes; D002850:Chromatography, Gel; D006851:Hydrochloric Acid; D008623:Mercaptoethanol; D010206:Papain / Q000032:analysis* / Q000037:antagonists & inhibitors; D010434:Pepsin A; D014357:Trypsin
chemical_list: D000085:Acetates; D002247:Carbon Isotopes; D008623:Mercaptoethanol; D014357:Trypsin; D010206:Papain; D010434:Pepsin A; D006851:Hydrochloric Acid