Polysialic acids occurrence

In reproductive biology, sialic acid polymers are receiving more and more attention. Polysialic acid with a(2-8)-linkages was found to be expressed on mouse embryos before and after implantation and the neuronal cell adhesion molecule (NCAM), which bears a polysialic acid chain, seems to be involved in cellular interactions in the early mammalian embryo [101,1076]. A similar function is attributed to polysialic acid observed during a short period of the larval stage of Drosophila melanogaster [1077]. It has to be noted that this is the first report on the occurrence of sialic acid in insects. 

Polysialic acid has been reported to undergo conformational changes in solution. Several left-handed helical epitopes with different pitches have been calculated and their relative occurrence in solution has been discussed [131, 132], Polysiahc acid bound to the cell surface adopts a similar average epitope as in solution [133], A sialic acid decamer is bound in an extended helix to the monoclonal antibody 735 [134], In contrast, a sialic acid pentamer has been described to bind endoNF in a compressed helical epitope [135] which has also been measured for polysialic acid in solution [132] and on the cell surface [133], Therefore, polysialic acid selectively undergoes conformational changes upon binding to endosiahdase or monoclonal antibody. 

Sato C, Kitajima K, Tazawa I, Inoue Y, Inoue S, Troy FA II (1993) Structural diversity in the o2-8-linked polysialic acid chains in sahnonid fish egg glycoproteins. Occurrence of poly (Neu5 Ac), poly(Neu5Gc), poly(Neu5Ac, Neu5Gc), poly(KDN), and their partially acetylated fimns. J Biol Chem 268 23675—23684... 

Kitazume S, Kitajima K, Inoue S, Troy FA, Cho JW, et al. Identification of polysialic acid-containing glycoprotein in the jelly coat of sea urchin eggs. Occurrence of a novel type of polysialic acid structure. J. Biol Chem. 1994 269 22712-22718. 

Natural Occurrence and Structure of Oligo-Polysialic Acid Chains... 

NATURAL OCCURRENCE AND STRUCTURE OF POLYSIALIC ACID-CONTAINING GLYCOCONJUGATES... 

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