Detection, isolation, and characterization of oligo/poly(sialic acid) and oligo/poly(deaminoneuraminic acid) units in glycoconjugates.

We have evaluated methods for separation, preparation, and characterization of alpha-2----8-linked oligomers of sialic acids (Neu5Ac and Neu5Gc) and deaminated neuraminic acid (KDN; 2-keto-3-deoxy-D-glycero-D-galacto-nononic acid) recently found as a naturally occurring novel type of sialic acid analogue. (A) We examined preparative anion-exchange chromatography for fractionation and preparation of oligo(Neu5Ac), oligo(Neu5Gc), and oligo(KDN). (B) We also examined the TLC method for separation and differentiation of the partial acid hydrolysates of colominic acid, as well as polysialoglycoproteins (PSGP) and poly(KDN)-glycoproteins (KDN-gp) isolated from rainbow trout eggs, and for discrimination of lower oligomers of Neu5Ac, Neu5Gc, and KDN. (C) We developed the high-performance adsorption-partition chromatographic method for (a) separation of monomers and oligomers of three nonulosonates according to the difference in substituents at C-5 and the presence or absence of 9-O-acetyl groups in oligo(KDN) and (b) separation of three homologous series of lower oligomers according to the degree of polymerization. (D) We examined and compared high-performance anion-exchange chromatographic separation of 3H-labeled oligo(Neu5Ac), oligo(Neu5Gc), and oligo(KDN) alditols by using Mono-Q HR 5/5 resin. (E) We examined a method of selective and quantitative microprecipitation for separation and purification of oligomers and polymers of Neu5Ac by treating them with cetylpyridinium chloride. We also used PSGP and KDN-gp to test both the sensitivity and the selectivity of this method.