Structure of Six 3‐Deoxy‐d‐Glycero‐d‐Galacto‐Nonulosonic Acid(Kdn)‐Containing Oligosaccharide‐Alditols Released from Oviduct Secretions of Ambystoma Maculatum

Abstract

TheO-linked acidic oligosaccharides of the jelly coat surrounding the eggs of Ambystoma maculatum were analyzed by NMR spectroscopy. The structures of the major oligosaccharides were established as follows where Kdn represents 3-deoxy-D-glycero-D-gakzcto-nonulosonic acid and GalNAc-ol is Nacetylgalactosaminitol :As shown for five other amphibian species, the structures of these carbohydrate chains appear to be species specific and can afford a basis for molecular taxonomy. These new sequences also reflect the occurrence of specific fucosyltransferase activities that are characteristic of Ambystoma maculatum.Keywords. Oligosaccharide structure ; amphibian egg jelly coats ; Ambystomu muculutum ; 'H,''C-NMR. Abbreviations. GalNAc-ol, N-acetylgalactosaminitol ; NeuAc, N-acetylneuraminic acid; Kdn, 3-deoxy-D-glycero-D-gnlactu-nonulosonic acid; COSY, correlation spectroscopy; ROESY, rotating-frame nuclear Overhauser enhancement spectroscopy ; HMQC, heteronuclear multiplequantum coherence.The glycoproteins surrounding the eggs of amphibians that constitute the main components from the oviduct, contain more than 50% carbohydrate and are essential for the fertilization process [I]. We have shown [2-41 that the carbohydrate structures are highly species specific and exhibit new and unusual features. In particular, 3-deoxy-D-glycero-D-gukzcto-nonulosonic acid (Kdn) is often the only acidic sugar component observed in many Urodeles (Axolotl, Pleurodeles) and Anurans ( R u m tem-

Structure elucidation of NeuAc, NeuGc and Kdn-containing O-glycans released from Triturus alpestris oviductal mucins

“…As previously observed [9][10][11][12], the presence of Kdn α-2-6-linked to GalNAc-ol, instead of NeuAc, is reflected by the absence of NAc signal at δ ≈ 2.03, whereas the H-3ax and H-3eq multiplets show upfield shifts of δ ≈ −0.04, as compared to the NeuAc analog. This structure might be elongated from C-3 branch to form either compound 31 or compound 38.…”

“…Kdn is now acknowledged to be an ubiquitous component of vertebrate glycoconjugates, owing to the remarkable contribution of Dr Yasuo Inoue in the field of Sialobiology [1,22,23]. It was later found as the sole sialic acid present in jelly coats of Pleurodeles and Ambystoma species [9][10][11][12]. In these cases, the Kdn unit formed a part of O-glycans based on type 1, 2 and 3 core structures.…”

“…The number of all possible linear and branched isomers of a hexasaccharide has been calculated and found to be higher than 10 12 [4]. This number appears higher than the number of living species on earth.…”

KDN (Deaminated neuraminic acid): Dreamful past and exciting future of the newest member of the sialic acid family

“…In oligosaccharide chains isolated from Mexican axolotl, and Xenopus laevis, KDN occurred as an internal residue to which a single Fuc or Fucα1 → 3Fuc unit was linked α1 → 4. In the egg jelly coat of other axolotl species (Ambystoma tigrinum, Ambystoma maculatum) KDN also occurred as internal residues monofucosylated at C4 or difucosylated at C4, and C5 [16][17][18]. Structures containing internal sialic acid substituted by sugar other than sialic acid are unusual for animal oligosaccharide units.…”