Model of photoprobe docking with beta 1,4-galactosyltransferase identifiesa possible carboxylate involved in glycosylation steps

A molecular docking study has been performed on the interaction of beta1,4- galactosyltransferase with an acceptor site photoprobe. This is based on an acceptor site peptide fragment which was recently identified by the use of a photoprobe. The present model strongly suggests that the carboxylate gro up of Asp318 could be involved in the activation of the acceptor sugar 4-OH for the efficient galactosyltransfer. The result also exemplified thar the combination of photoaffinity labeling with crystallography is a powerful m ethod for the detailed structural analysis of ligand-protein complex. (C) 2 001 Elsevier Science Ltd. All rights reserved.