title: The heparin-binding site of human xanthine oxidase.
abstract: The enzyme xanthine oxidase (XOD) has an affinity for heparin and can bind to cultured porcine aortic endothelial cells. We have reported that the exposure of human XOD (h-XOD) to the lysine-specific reagent trinitrobenzenesulfonic acid or the arginine-specific reagent phenylglyoxal caused it to lose its affinity for heparin-Sepharose. The heparin-binding sites in h-XOD are further studied in the present article. From a chymotryptic digest of cyanogen bromide fragmented h-XOD, two peptides with an affinity for heparin-HPLC, A-1 and A-2, were isolated. Amino acid sequence analysis showed that both peptides had lysine and/or arginine residues. The A-1 region may direct its charged side chains toward the solvent while burying its hydrophobic side chains against the hydrophobic inside, because the A-1 peptide forms a highly amphipathic structure. Peptide A-2 contains triple lysine residues and constitutes a hydrophilic region.
authors.affiliation: Department of Pharmaceutics, Gifu Pharmaceutical University, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Fukushima
authors.forename: T
authors.initials: T
authors.lastname: Adachi
authors.forename: K
authors.initials: K
authors.lastname: Hirano
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D002851:Chromatography, High Pressure Liquid; D002918:Chymotrypsin; D003488:Cyanogen Bromide; D006493:Heparin / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000302:isolation & purification; D014969:Xanthine Oxidase / Q000378:metabolism*
chemical_list: D010455:Peptides; D006493:Heparin; D014969:Xanthine Oxidase; D002918:Chymotrypsin; D003488:Cyanogen Bromide