Presence of the protein-glycosaminoglycan-protein covalent cross-link in the inter-alpha-inhibitor-related proteinase inhibitor heavy chain 2/bikunin.

Published

Journal Article

HC2/bikunin is a human plasma proteinase inhibitor composed of two polypeptide chains that resist dissociation under reducing conditions in SDS-polyacrylamide gel electrophoresis. This observation suggests that a nondisulfide cross-link is responsible for the association of these two polypeptide chains. In this study, we have utilized a variety of techniques to investigate the structural basis for this observation. We show that the cross-link between the two protein chains is sensitive to chondroitin sulfate-degrading enzymes and to 50 mM NaOH, properties shared by the protein-glycosaminoglycan-protein cross-link found in the related pre-alpha-inhibitor (Enghild, J. J., Salvesen, G., Hefta, S., Thøgersen, I. B., Rutherfurd, S., and Pizzo, S. V. (1991) J. Biol. Chem. 266, 747-751). Biochemical and mass spectrometric analysis of the peptides containing the cross-link indicate that it is mediated by a chondroitin-4-sulfate chain that originates from a typical O-glycosidic link to Ser10 of bikunin. The COOH-terminal Asp648 residue of heavy chain 2 is esterified via the alpha-carbon to C-6 of an internal N-acetylgalactosamine of the chondroitin-4-sulfate chain. This suggests that the protein-glycosaminoglycan-protein cross-link that assembles the chains of pre-alpha-inhibitor is identical to that which assembles HC2/bikunin, and is probably a characteristic of the bikunin proteins.

Full Text

Duke Authors

Cited Authors

  • Enghild, JJ; Salvesen, G; Thøgersen, IB; Valnickova, Z; Pizzo, SV; Hefta, SA

Published Date

  • April 25, 1993

Published In

Volume / Issue

  • 268 / 12

Start / End Page

  • 8711 - 8716

PubMed ID

  • 7682553

Pubmed Central ID

  • 7682553

International Standard Serial Number (ISSN)

  • 0021-9258

Language

  • eng

Conference Location

  • United States