Rf. Sala et al., UDP-N-TRIFLUOROACETYLGLUCOSAMINE AS AN ALTERNATIVE SUBSTRATE IN N-ACETYLGLUCOSAMINYLTRANSFERASE REACTIONS, Carbohydrate research, 306(1-2), 1998, pp. 127-136
The synthesis of UDP-N-trifluoroacetylglucosamine [uridine -trifluoroa
cetamido-2-deoxy-alpha-D-glucopyranosyl diphosphate, UDP-GlcNAc-F-3] i
s reported. The compound is found to serve as a substrate for the 'cor
e-2' GlcNAc transferase (EC 2.4.1.102) that is involved in the biosynt
hesis, of O-linked glycoproteins and for the GlcNAcT-V transferase (EC
2.4. 1.155) that is a key biosynthetic enzyme controlling the branchi
ng pattern of cell surface complex Asn-linked oligosaccharides. The tr
isaccharide beta-o-Gal p-(1 --> 3)-[beta-D-GlcpNAc-F-3(1 --> 6)]alpha-
D-GalpNAc-OR [R = (CH2)(8)CO2Me] was prepared from beta-D-Galp-(1 -->
3)-alpha-D-GalpNAc-OR using the 'core-2' GlcNAc transferase. The tetra
saccharide beta-D-GlcpNAc-(1 --> 2)-[beta-D-GlcpNAc-F-3-(1 --> 6)]-alp
ha-D-Manp-(1 --> 6)-beta-D-Glcp-OR [R = (CH2)(7)CH3] was prepared from
beta-D-GlcpNAc-(1 --> 2)-alpha-D-Manp-(1 --> 6)-beta-D-Glcp-OR [R = (
CH2)(7)CH3] using the GlcNAcT-V transferase. Removal of the trifluoroa
cetyl group was achieved under mild basic conditions to give the corre
sponding glucosamine containing tetrasaccharide. These examples demons
trate the feasibility of introducing masked forms of glucosamine resid
ues into oligosaccharides using GlcNAc-specific transferases. The requ
irement for the trifluoroacetamido group as a specific recognition ele
ment was evident in the observation that neither UDP-glucosamine nor U
DP-glucose served as a donor substrates for the 'core-2' GlcNAc transf
erase. (C) 1998 Elsevier Science Ltd. All rights reserved.