Issue 13, 2011

A mechanistic study of sialic acid mutarotation: Implications for mutarotase enzymes

Abstract

The mutarotation of N-acetylneuraminic acid (Neu5Ac) proceeds by four kinetically distinct pathways: (i) the acid-catalyzed reaction of neutral Neu5Ac; (ii) the spontaneous reaction of the carboxylic acid (the kinetically equivalent acid-catalyzed reaction on the anion being ruled out by the solvent deuterium kinetic isotope effect of 3.74 ± 0.68); (iii) a spontaneous, water-catalyzed, reaction of the anion; and (iv) a specific-base catalyzed reaction of the anion. The magnitude of the solvent kinetic isotope effect, kH2O/kD2O = 4.48 ± 0.74 is consistent with a ring-opening transition state in which a water molecule is deprotonating the anomeric hydroxyl group in concert with strengthening solvation of the ring oxygen atom. The mechanistic implications for Neu5Ac mutarotases are discussed.

Graphical abstract: A mechanistic study of sialic acid mutarotation: Implications for mutarotase enzymes

Supplementary files

Article information

Article type
Paper
Submitted
14 Jan 2011
Accepted
11 Apr 2011
First published
12 Apr 2011

Org. Biomol. Chem., 2011,9, 4818-4822

A mechanistic study of sialic acid mutarotation: Implications for mutarotase enzymes

J. Chan, G. Sandhu and A. J. Bennet, Org. Biomol. Chem., 2011, 9, 4818 DOI: 10.1039/C1OB05079F

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