Importance of specific amino acids in protein binding sites for heparin and heparan sulfate

Elizabeth E.O. Caldwell, Varsha D. Nadkarni, Jonathan R. Fromm, Robert J. Linhardt, John M. Weiler

Research output: Contribution to journalArticlepeer-review

59 Scopus citations

Abstract

Heparin and heparan sulfate bind a variety of proteins and peptides to regulate many biological activities. Past studies have examined a limited number of established heparin binding sites and have focused on basic amino acids when modeling binding site structural motifs. This study examines the prevalence of individual amino acids in peptides binding to heparin or heparan sulfate. A 7-mer random peptide library was synthesized using the 20 common amino acids. This 7-mer library was affinity separated using both heparin and heparan sulfate-Sepharose. Bound peptide populations were eluted with a salt step gradient (pH 7) and analysed for amino acid composition. Peptides released from heparin-Sepharose by 0.3 M NaCl were enriched in arginine, lysine, glycine and serine; and depleted in methionine and phenylalanine. In contrast, peptides released from heparan sulfate-Sepharose were enriched in arginine, glycine, serine, and proline (at 0.15 M NaCl). These peptides were depleted in histidine, isoleucine, methionine (not detectable) and phenylalanine. In the heparin binding sites of proteins, which have been published, the enriched amino acids were arginine, lysine and tyrosine. Depleted amino acids include aspartic acid, glutamic acid, glutamine, alanine, glycine, phenylalanine, serine, threonine and valine. This study demonstrates that heparin and heparan sulfate bind different populations of peptide sequences. The differences in amino acid composition indicate that the positive charge density and spacing requirements differ for peptides binding these two glycosaminoglycans.

Original languageEnglish
Pages (from-to)203-216
Number of pages14
JournalInternational Journal of Biochemistry and Cell Biology
Volume28
Issue number2
DOIs
StatePublished - Feb 1996
Externally publishedYes

Keywords

  • Glycosaminoglycan-protein interactions
  • Heparan sulfate
  • Heparin
  • Peptide library

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