title: Differential reactivity of two types of N-glycolyneuraminic acid dimers toward enzymatic and nonenzymatic hydrolysis of their interketosidic linkages.
abstract: The kinetics of acid- and sialidase-catalyzed hydrolysis of the interketosidic linkages of two different disialic acids, Neu5Gc alpha 2-->5-OglycolylNeu5Gc and Neu5Gc alpha 2-->8Neu5Gc, were studied. The former sequence was recently identified in the polysialic acid chains of a sialic acid-rich glycoprotein isolated from the egg jelly coat of two different species of sea urchins, and the latter was previously found in the cortical alveolar-derived polysialoglycoprotein from rainbow trout eggs. At pH values < 3.8, the rate of hydrolysis of Neu5Gc alpha 2-->5-OglycolylNeu5Gc was greater than that of Neu5Gc alpha 2-->8Neu5Gc. Paradoxically, however, Neu5Gc alpha 2-->5-OglycolylNeu5Gc was more stable than Neu5Gc alpha 2-->8Neu5Gc at pH values > 3.8. These findings indicate a greater contribution of intramolecular general acid catalysis to the lability of the alpha 2-->5-ketosidic linkage. Neu5Gc alpha 2-->5-OglycolylNeu5Gc was a poor substrate for Arthrobacter ureafaciens, Clostridium perfringens, and Vibrio cholerae sialidases, in contrast to Neu5Gc alpha 2-->8Neu5Gc. Neu5Gc alpha 2-->5-OglycolylNeu5Gc was essentially resistant to hydrolysis by A. ureafaciens sialidase.
authors.affiliation: Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Kitazume
authors.forename: K
authors.initials: K
authors.lastname: Kitajima
authors.forename: S
authors.initials: S
authors.lastname: Inoue
authors.forename: F A
authors.initials: FA
authors.lastname: Troy
authors.forename: W J
authors.initials: WJ
authors.lastname: Lennarz
authors.forename: Y
authors.initials: Y
authors.lastname: Inoue
mesh_terms: D002240:Carbohydrate Sequence; D002384:Catalysis; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D008969:Molecular Sequence Data; D009438:Neuraminic Acids / Q000737:chemistry*; D009439:Neuraminidase / Q000737:chemistry; D011108:Polymers
chemical_list: D009438:Neuraminic Acids; D011108:Polymers; C032592:N-glycolylneuraminic acid; D009439:Neuraminidase