Differential reactivity of two types of N-glycolyneuraminic acid dimers toward enzymatic and nonenzymatic hydrolysis of their interketosidic linkages.
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.
Kitazume
S
S
Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, Japan.
Kitajima
K
K
Inoue
S
S
Troy
F A
FA
Lennarz
W J
WJ
Inoue
Y
Y
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
D009438:Neuraminic Acids; D011108:Polymers; C032592:N-glycolylneuraminic acid; D009439:Neuraminidase