beta-Hydroxyaspartic acid in vitamin K-dependent protein C.
Previous work has shown that the light chain of protein C, an anticoagulant plasma protein, contains an unusual amino acid [Fernlund, P. & Stenflo, J. (1982) J. Biol. Chem. 257, 12170-12179]. To determine the structure of this amino acid a heptapeptide, CMCys-Ile-X-Gly-Leu-Gly-Gly (residues 69-75 in the light chain), was isolated from enzymatic digests of the light chain. According to automatic Edman sequence analysis, 1H NMR spectroscopy, and mass spectrometry the heptapeptide had beta-hydroxyaspartic acid in its third position, which corresponds to position 71 in the light chain of protein C. Analysis of acid and aminopeptidase M hydrolysates of the heptapeptide showed the beta-hydroxyaspartic acid to be the erythro form. Acid hydrolysis of protein C released approximately equal to 1 mol of beta-hydroxyaspartic acid per mol of protein. The function of this amino acid, which, to the best of our knowledge, has not been found previously in proteins, is unknown.
D000595:Amino Acid Sequence; D000818:Animals; D001224:Aspartic Acid / Q000031:analogs & derivatives*; D001779:Blood Coagulation Factors; D002417:Cattle; D006023:Glycoproteins; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D010446:Peptide Fragments / Q000032:analysis; D011486:Protein C; D014812:Vitamin K
D001779:Blood Coagulation Factors; D006023:Glycoproteins; D010446:Peptide Fragments; D011486:Protein C; D014812:Vitamin K; D001224:Aspartic Acid