Substrate specificity of the heparan sulfate hexuronic acid 2-O-sulfotransferase.

摘要: The interaction of heparan sulfate with different ligand proteins depends on the precise location O-sulfate groups in polysaccharide chain. We have previously shown that overexpression human kidney 293 cells a mouse mastocytoma 2-O-sulfotransferase (2-OST), thought to catalyze transfer from 3'-phosphoadenosine 5'-phosphosulfate C2 L-iduronyl residues, preferentially increases level 2-O-sulfation D-glucuronyl units [Rong, J., Habuchi, H., Kimata, K., Lindahl, U., and Kusche-Gullberg, M. (2000) Biochem. J. 346, 463-468]. In study presented here, we further investigated substrate specificity 2-OST. Different acceptor substrates were incubated cell extracts 2-OST-transfected together donor 5'-phospho[(35)S]sulfate. Incubations O-desulfated heparin, predominantly composed [(4)alphaIdoA(1)-(4)alphaGlcNSO(3)(1)-](n)(), resulted iduronic acid. When, other hand, an N-sulfated capsular Escherichia coli K5, structure [(4)betaGlcA(1)-(4)alphaGlcNSO(3)(1)-](n)(), was used as acceptor, transferred almost exclusively glucuronic Substrates containing both acid residues about equal proportions strongly favored sulfation agreement these results, 2-OST found approximately 5-fold higher affinity for acid-containing disaccharide (K(m) 3.7 microM) than 19.3 microM).