Bintein F, Augé C, Lubineau A. Chemo-enzymatic synthesis of a divalent sialyl Lewis(x) ligand with restricted flexibility.
Carbohydr Res 2003;
338:1163-73. [PMID:
12747858 DOI:
10.1016/s0008-6215(03)00129-0]
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Abstract
To study the influence of the entropic factor in cluster cooperative effects, a divalent sialyl Lewis(x) ligand with restricted flexilbility was chemo-enzymatically synthesized. First, a cyclized precursor with both glucosamine residues bridged together by a succinyl group was readily obtained in 42% yield by treatment of 2,2-bis(benzyloxymethyl)-1,3-bis(3,4,6-tri-O-acetyl-2-amino-2-deoxy-beta-D-glucopyranosyloxy)-propane with succinyl chloride. After deacetylation, this precursor was subjected to stepwise enzymatic elongation utilizing successively, soluble galactosyltransferase, then recombinant sialyltransferase and fucosyltransferase; the latter enzymes immobilized on Ni(2+)-Agarose, to afford, after debenzylation, a divalent sialyl Lewis(x) ligand of restricted flexibility, in 45% overall yield. Following the same enzymatic sequence, a totally flexible ligand, required as a reference compound for evaluation of inhibitory activity toward selectins, was also prepared from 2,2(bis-benzyloxymethyl)-1,3-bis(2-acetamido-2-deoxy-beta-D-glucopyranosyloxy)-propane, as well as both related divalent Lewis(x) molecules lacking the sialic acids, the rigid one and the flexible one.
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