Diastereomeric Glycosyl Sulfoxides Display Different Recognition Features versus E. coli β-Galactosidase

Abstract

The conformational analysis of the (S) and (R) diastereoisomers of benzyl 3-deoxy-4S-(β-d-galactopyranosyl)-4-thio-β-d-threo-pentopyranoside S-oxide (1S and 1R, respectively) has been performed by using NMR spectroscopy assisted by molecular modelling methods. The results point out that sulfoxide 1S and 1R display rather different conformational behaviors, 1S being significantly more flexible than 1R. Both sulfoxides have shown to be competitive inhibitors of the β-galactosidase from E. coli, although with different potencies. The key structural features of the molecular recognition process have been characterized.