Glycosyltransferase mechanisms: Impact of a 5-fluoro substituent in acceptor and donor substrates on catalysis

Matthew C.T. Hartman, Songmin Jiang, Jeffrey S. Rush, Charles J. Waechter, James K. Coward

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


In glycosyltransferase-catalyzed reactions a new carbohydrate-carbohydrate bond is formed between a carbohydrate acceptor and the carbohydrate moiety of either a sugar nucleotide donor or lipid-linked saccharide donor. It is currently believed that most glycosyltransferase-catalyzed reactions occur via an electrophilic activation mechanism with the formation of an oxocarbenium ion-like transition state, a hypothesis that makes clear predictions regarding the charge development on the donor (strong positive charge) and acceptor (minimal negative charge) substrates. To better understand the mechanism of these enzyme-catalyzed reactions, we have introduced a strongly electron-withdrawing group (fluorine) at C-5 of both donor and acceptor substrates in order to explore its effect on catalysis. In particular, we have investigated the effects of the 5-fluoro analogues on the kinetics of two glycosyltransferase-catalyzed reactions mediated by UDP-GlcNAc:GlcNAc-P-P-Dol N-acetylglucosaminyltransferase (chitobiosyl-P-P-lipid synthase, CLS) and β-N-acetylglucosaminyl-β-1,4 galactosyltransferase (GalT). The 5-fluoro group has a marked effect on catalysis when inserted into the UDP-GlcNAc donor, with the UDP(5-F)-GlcNAc serving as a competitive inhibitor of CLS rather than a substrate. The (5-F)-GlcNAc β-octyl glycoside acceptor, however, is an excellent substrate for GalT. Both of these results support a weakly associative transition state for glycosyltransferase-catalyzed reactions that proceed with inversion of configuration.

Original languageEnglish
Pages (from-to)11630-11638
Number of pages9
Issue number41
StatePublished - Oct 16 2007

ASJC Scopus subject areas

  • Biochemistry


Dive into the research topics of 'Glycosyltransferase mechanisms: Impact of a 5-fluoro substituent in acceptor and donor substrates on catalysis'. Together they form a unique fingerprint.

Cite this