@article { ISI:000224716400002,
	title = {The synthesis of a series of modified mannotrisaccharides as probes of the enzymes involved in the early stages of mammalian complex N-glycan formation},
	journal = {CARBOHYDRATE RESEARCH},
	volume = {339},
	number = {15},
	year = {2004},
	month = {OCT 20},
	pages = {2487-2497},
	abstract = {A series of mannotrisaccharides were synthesized by two distinct chemical pathways as probes of the enzymes involved in the early stages of mammalian complex N-glycan formation. Methyl (alpha-D-mannopyranosyl)-(1{\textendash}>3)-{[}(alpha-D-mannopyranosyl)-(1{\textendash}>6)]-be ta-D-mannopyranoside (6) and methyl (2-deoxy-2-fluoro-alpha-D-mannopyranosyl)-(1{\textendash}>3)-{[}(2-deoxy-2-fluoro-a lpha-D-mannopyranosyl)(1{\textendash}>6)]-{[}beta-D-mannopyranoside (8) were rapidly synthesized from unprotected methyl beta-D-mannopyranoside (12). Methyl (2-deoxy-2-fluoro-alpha-D-mannopyranosyl)-(1{\textendash}>3)-{[}(alpha-D-mannopyran osyl)-(1{\textendash}>6)]-beta-D-mannopyranoside (7) and methyl (alpha-D-mannopyranosyl)-(1{\textendash}>3)-{[}(2-deoxy-2-fluoro-alpha-D-mannopyran osyl)-(1{\textendash}>6)]-beta-D-mannopyranoside (9) were synthesized from the common orthogonally protected precursor methyl 2-O-acetyl-4,6-O-benzylidene-beta-D-mannopyranoside (15). The 2-deoxy-2-fluoro substitution common to trisaccharides 7-9 renders these analogues resistant to enzyme action in two distinct ways. Firstly the fluorine serves as a non-nucleophilic isostere for the acceptor hydroxyl in studies with glycosyl transferases GnT-I and GnT-II (7 and 9, respectively). Secondly it should render trisaccharide 8 stable to hydrolysis by the mannosidases Man-II and Man-III by inductive destabilization of their oxocarbenium ion-like transition states. These analogues should be useful for structural studies on these enzymes. (C) 2004 Elsevier Ltd. All rights reserved.},
	issn = {0008-6215},
	doi = {10.1016/j.carres.2004.08.007},
	author = {Tarling, CA and Withers, SG}
}
