Sialic acids (N,7-O-diacetylneuraminic acid and N-acetylneuraminic acid) in Escherichia coli. I. Isolation and identification.

DeWitt, Charles W. (The Upjohn Co., Kalamazoo, Mich.) and Janet A. Rowe. Sialic acids (N,7-O-diacetylneuraminic acid and N-acetylneuraminic acid) in Escherichia coli. I. Isolation and identification. J. Bacteriol. 82:838-848. 1961.-Two sialic acids, N-acetylneuraminic acid and N,7-O-diacetylneuraminic acid, were obtained in crude mixtures from whole cells of Escherichia coli and from its endotoxin by weak acid hydrolysis followed by anion exchange resin chromatography. Yields from whole cells were 0.1 to 0.2% (dry weight) with 50 to 60% purity. Identification of the sialic acids was by comparative paper chromatography and colorimetric assays using the acidic p-dimethylaminobenzaldehyde (direct Ehrlich), resorcinol and thiobarbituric acid reactions. The N-acetyl derivative was also shown to be susceptible to hydrolysis by clostridial N-acetylneuraminic aldolase and the end products identified, N-acetylamannosamine by paper chromatography and pyruvic acid by oxidation of DPNH with lactic acid dehydrogenase. The two sialic acids were separated on paper chromatograms, eluted, and assays for total and ester acyl groups showed the suspected N-acetyl derivative to contain 0.11 O-acyl and 1.16 N-acetyl groups per mole sialic acid and the diacetyl derivative to have 1.10 O-acyl and 0.93 N-acetyl groups per mole. The O-acyl group was identified as acetyl by preparation of the hydroxamate.