A novel disaccharide substrate having 1,2-oxazoline moiety for detection of transglycosylating activity of endoglycosidases

A disaccharide substrate of Man beta1-4GIcNAc-oxazoline 2 was designed and synthesized as a novel probe for detection of the transglycosylating activi ty of endoglycosidases. A regio- and stereoselective transglycosylation rea ction of 2 to GlcNAc beta1-O-pNP or DrisAsn(GlcNAc)-OH catalyzed by endo-be ta -N-acetylglucosaminidase from Mucor hiemalis (Endo-M) and endo-beta -N-a cetylglucosaminidase from Arthrobacter protophormiae (Endo-A) has been demo nstrated for the first time, resulting in the core trisaccharide derivative Man beta 4GlcNAc beta1-4GlcNAc beta1-O-pNP 8 (or -(Dns)Asn-OH). Interestin gly, the transglycosylation proceeds irreversibly; the resulting trisacchar ide 8 was not hydrolyzed by Endo-M and Endo-A. Based on these results, a ne w mechanism including an oxazolinium ion intermediate has been proposed for the endoglycosidase-catalyzed hydrolysis or transglycosylation. (C) 2001 E lsevier Science BY. All rights reserved.