New Sialic Acids

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Abstract
Sialic acids were released by dilute acids or by neuraminidase from glycoproteins of bovine and equine submandibular glands, from glycoproteins of equine blood plasma and from equine erythrocyte membranes. They were purified by ion‐exchange chromatography and fractionated on cellulose. The following methods have been adapted to the structural analysis of sialic acids with regard to the nature and position of the N‐acyl and O‐acyl groups.a) Thin‐layer chromatography in two dimensions with intermediate ammonia treatment to remove the O‐acyl groups leading to the identification of the basic N‐acylneuraminic acids.b) Thin‐layer chromatography in two dimensions with intermediate hydroxylamine treatment allowing the identification of the O‐acyl groups of sialic acids as hydroxamates.c) Gas‐liquid chromatography for identification of the different N‐acylated and O‐acylated sialic acids. The structure of the following new sialic acids have been established:a) N‐glycoloyl‐8‐O‐acetylneuraminic acid isolated from glycoproteins of bovine submandibular glands;b) N‐acetyl‐4‐O‐glycoloylneuraminic acid isolated from glycoproteins of equine submandibular glands and also occurring in equine blood plasma and equine erythrocyte membranes;c) N‐acetyl‐7 or 8‐O‐glycoloylneuraminic acid detected in glycoproteins from bovine submandibular glands. The O‐acetylated N‐glycoloylneuraminic acid first detected in horse erythrocyte membranes by Hakomori and Saito and in horse serum by Pepper, was determined to be N‐glycoloyl‐4‐O‐acetyl‐neuraminic acid; it was also found to occur in submandibular glands of horse. The sialic acid patterns from the different biological materials investigated are compared.

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