title: Intrachain disulfide bridges of bovine seminal ribonuclease.
abstract: The pairing of the four intrachain disulfide bonds of bovine seminal ribonuclease, a dimeric protein isolated from bovine seminal plasma, has been established by the isolation and characterization of the cystine peptides obtained from a thermolytic-tryptic hydrolysate of the protein. These disulfide bonds involve eight half-cystine residues located in the protein subunit chain at sequence positions identical with those of the eight half-cystine residues of the strictly homologous chain of bovine pancreatic ribonuclease. The results reported show that these eight 'homologous' half-cystine residues pair in seminal ribonuclease exactly as they do in pancreatic ribonuclease. They also indirectly confirm that the remaining two half-cystine residues present in each chain of the seminal enzyme are involved in intersubunit bonds.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001952:Bridged-Ring Compounds; D002417:Cattle; D055598:Chemical Phenomena; D002621:Chemistry; D003553:Cystine / Q000032:analysis; D004220:Disulfides / Q000032:analysis*; D008297:Male; D010179:Pancreas / Q000201:enzymology; D012260:Ribonucleases; D012661:Semen / Q000201:enzymology
chemical_list: D001952:Bridged-Ring Compounds; D004220:Disulfides; D003553:Cystine; D012260:Ribonucleases