title: A semisynthetic bovine pancreatic ribonuclease containing a unique nitrotyrosine residue.
abstract: A fully active semisynthetic ribonuclease, RNase 1-118:111-124, may be prepared by enzymatically removing six residues from the COOH terminus of the protein (positions 119-124) and then complementing the inactive RNase 1-118 with a chemically synthesized peptide containing the COOH-terminal 14 residues of the molecule (RNase 111-124) [M. C. Lin, B. Gutte, S. Moore, and R. B. Merrifield (1970) J. Biol. Chem. 245, 5169-5170]. Nitration of tyrosine-115 in the peptide followed by complex formation with RNase 1-118 affords a fully active enzyme containing a unique nitrotyrosine residue in a position which is known and which is very likely to be completely exterior to the active site region. The binding constant between the tetradecapeptide and RNase 1-118 (5 X 10(6) M-1 at pH 6.0) is not changed by the nitration. Crystals of the nitrated complex are isomorphous with those of RNase 1-118:111-124, for which a refined 1.8-A structure has recently been obtained.
mesh_terms: D000818:Animals; D002417:Cattle; D003461:Crystallography; D007700:Kinetics; D009566:Nitrates; D009842:Oligopeptides / Q000138:chemical synthesis; D010179:Pancreas / Q000201:enzymology; D011487:Protein Conformation; D012260:Ribonucleases / Q000378:metabolism; D013057:Spectrum Analysis; D013329:Structure-Activity Relationship; D014443:Tyrosine / Q000031:analogs & derivatives*
chemical_list: D009566:Nitrates; D009842:Oligopeptides; D014443:Tyrosine; D012260:Ribonucleases