Asparagine 405 of heparin lyase II prevents the cleavage of glycosidic linkages proximate to a 3-O-sulfo glucosamine residue

Abstract

Heparin and heparan sulfate contain a rare 3-O-sulfoglucosamine residue critical for anticoagulation and virus recognition, respectively. The glycosidic linkage proximate to this 3-O-sulfoglucosamine is resistant to cleavage by all heparin lyases. Heparin lyase II has a broad specificity. The crystal structure of the wild type heparin lyase II identified its active site and showed a close spatial proximity between Asn405 and the 3-OH group of the bound glucosamine residue. In this study, we mutated Asn405 to the less sterically demanding Ala405 or Gly405, which broadened the substrate specificity of heparin lyase II and caused it to cleave the resistant linkage proximate to the 3-O-sulfoglucosamine residue.