@article { ISI:000172450400080,
	title = {Biochemical and structural assessment of the 1-N-azasugar GalNAc-isofagomine as a potent family 20 beta-N-acetylhexosaminidase inhibitor},
	journal = {JOURNAL OF BIOLOGICAL CHEMISTRY},
	volume = {276},
	number = {45},
	year = {2001},
	month = {NOV 9},
	pages = {42131-42137},
	abstract = {Azasugar inhibitors of the isofagomine class are potent competitive inhibitors of configuration-retaining beta -glycosidases. This potency results from the formation of a strong electrostatic interaction between a protonated endocyclic nitrogen at the {\textquoteleft}{\textquoteleft}anomeric{{\textquoteright}{\textquoteright}} center of the inhibitor and the catalytic nucleophile of the enzyme. Although the majority of retaining beta -glycosidases use a mechanism involving a carboxylate residue as a nucleophile, Streptomyces plicatus beta -N-acetylhexosaminidase (SpHEX) and related family 20 glycosidases lack such a catalytic residue and use instead the carbonyl oxygen of the 2-acetamido group of the substrate as a nucleophile to {\textquoteleft}{\textquoteleft}attack{{\textquoteright}{\textquoteright}} the anomeric center. Thus, a strong electrostatic interaction between the inhibitor and enzyme is not expected to occur; nonetheless, the 1-N-azasugar (2R,3R,4S,5R)-2-acetamido-3,4-dihydroxy5-hydroxymethyl-piperidinium hydrochloride (Ga1NAc-isofagomine . HCl), which was synthesized and assayed for its ability to inhibit SpHEX, was found to be a potent competitive inhibitor of the enzyme (K-i = 2.7 mum). A crystallographic complex of Ga1NAc-isofagomine bound to SpHEX was solved and refined to 1.75 Angstrom and revealed that the lack of a strong electrostatic interaction between the {\textquoteleft}{\textquoteleft}anomeric{{\textquoteright}{\textquoteright}} center of Ga1NAc-isofagomine and SpHEX is compensated for by a novel 2.8-Angstrom hydrogen bond formed between the equatorial proton of the endocyclic nitrogen of the azasugar ring and the carboxylate of the general acid-base residue Glu-314 of SpHEX. This interaction appears to contribute to the unexpected potency of Ga1NAc-isofagomine toward SpHEX.},
	issn = {0021-9258},
	doi = {10.1074/jbc.M107154200},
	author = {Mark, BL and Vocadlo, DJ and Zhao, DL and Knapp, S and Withers, SG and James, MNG}
}
