Sugar nucleotide recognition by Klebsiella pneumoniaeUDP-d-galactopyranose mutase: Fluorinated substrates, kinetics and equilibria?

Organic & Biomolecular Chemistry Pub Date: 2009-01-23 DOI: 10.1039/B815549F

Abstract

A series of selectively fluorinated and other substituted UDP-D-galactose derivatives have been evaluated as substrates for Klebsiella pneumoniaeUDP-D-galactopyranose mutase. This enzyme, which catalyses the interconversion of the pyranose and furanose forms of galactose as its UDP adduct, is a prospective drug target for a variety of microbial infections. We show that none of the 2″-, 3″- or 6″-hydroxyl groups of UDP-D-galactopyranose are essential for substrate binding and turnover. However, steric factors appear to play an important role in limiting the range of substitutions that can be accommodated at C-2″ and C-6″ of the sugar nucleotide substrate. Attempts to invert the C-2″ stereochemistry from equatorial to axial, changing D-galacto- to D-talo-configuration, in an attempt to exploit the higher percentage of furanose at equilibrium in the talo-series, met with no turnover of substrate.

Graphical abstract: Sugar nucleotide recognition by Klebsiella pneumoniaeUDP-d-galactopyranose mutase: Fluorinated substrates, kinetics and equilibria
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