Synthesis of seleno-fucose compounds and their application to the X-ray structural determination of carbohydrate-lectin complexes using single/multi-wavelength anomalous dispersion phasing.

Selenium-incorporated fucoses (seleno-fucoses) differing in the position of the seleno-substituent were synthesized and applied to the X-ray structural determination of a carbohydrate-lectin complex using single/multi-wavelength anomalous dispersion (SAD/MAD) phasing. The hydroxyl groups at the C-1, -2, -3 and -4 position of fucose were individually substituted with a methylseleno group via a transacetalization reaction using MeSeCHOBn or by an S2 reaction with TolSe equivalents to afford the corresponding MeSe-fucose. The three-dimensional structures of a fucose-binding lectin complexed with several of these MeSe-fucoses have been determined by SAD/MAD phasing by utilizing the diffraction of selenium in the bound MeSe-fucoses.