期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1979
卷号：76
期号：9
页码：4313-4316
DOI：10.1073/pnas.76.9.4313
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Methylamine reacts with the plasma protease inhibitor, alpha 2-macroglobulin, to form an irreversible, covalent modification. Quantitation of the reaction indicates 3.9 +/- (SD) 0.4 reactive sites per native tetrameric protein (Mr = 725,000) or one site per subunit. The reaction is selective and specific in that only 1 or 2 labeled peptides are observed on radioautography of peptide maps derived from [14C]methylamine-treated alpha 2-macroglobulin. A single chymotryptic peptide was isolated in 56% overall yield from the labeled protein. The peptide sequence by Edman degradation was found to be Gly-Cys-Gly-Glu-X-Asn-Met-(Val, Leu), in which X was the only radiolabeled phenylthiohydantoin derivative. Amino acid analysis and mass spectral analysis of the derivative suggests that X is gamma-glutamylmethylamide. Because glutamic acid and glutamine residues do not normally react with alkylamines, this work presents presumptive evidence for an alternative activated center in selected proteins.
