Periodate oxidation of α-(2→8)-linked polysialic acid PSA has frequently been used to generate an aldehyde group at C7 of the distal end unit of the polysaccharide chain to be used in subsequent conjugation to protein carriers [1,2]. In-depth analysis of reaction products ranging from Neu5Ac mono- to tetramers, 4 kDa and 20 kDa polymers and their respective periodate-oxidized products by high-field NMR spectroscopy allowed for a detailed analysis of non-degenerate signals at both reducing and non-reducing termini, respectively. Moreover, the presence of a free 7-aldehyde group could be excluded. Instead, oxidation of both anomeric Me glycosides gave the 7-hydrated aldehyde products, whereas oxidation of the oligomeric and polymeric substrates led to interresidue hemiacetal formation extending from C7 of the terminal end group to O-9 of the neighboring Neu5Ac residue [3]. Acknowledgment The oxidized 4 kDa polysialic acid material was kindly provided by Serum Institute of India Ltd. Refs: [1] M. Mühlenhoff et al., Curr. Opinion Struct. Biol. 1998 (8) 558. [2] L.M. Krug et al., Clin. Cancer Res. 2004 (10) 916. [3] G.J. Ray, N. Ravenscroft, J. Siekmann, Z. Zhang, P. Sanders, U. Shaligram, C. M. Szabo, P. Kosma, Bioconj. Chem. 2014 (25) 665.

NMR analysis of periodate-oxidation products of 5-N-acetylneuraminic acid methyl glycosides and 2,8-polysialic acid (PSA)

249th National Meeting (2015)

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