Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If You Use a Screen Reader

This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.

Characterization of Alkylamine-Sensitive Site in α 2-macroglobulin

Richard P. Swenson and James Bryant Howard
Proceedings of the National Academy of Sciences of the United States of America
Vol. 76, No. 9 (Sep., 1979), pp. 4313-4316
Stable URL: http://www.jstor.org/stable/70075
Page Count: 4
  • Read Online (Free)
  • Subscribe ($19.50)
  • Cite this Item
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Characterization of Alkylamine-Sensitive Site in α 2-macroglobulin
Preview not available

Abstract

Methylamine reacts with the plasma protease inhibitor, α 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 α 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 γ -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.

Page Thumbnails

  • Thumbnail: Page 
4313
    4313
  • Thumbnail: Page 
4314
    4314
  • Thumbnail: Page 
4315
    4315
  • Thumbnail: Page 
4316
    4316