Chemical structures of oligosaccharides in milk of the raccoon (Procyon lotor)

Abstract

In this study on milk saccharides of the raccoon (Procyonidae: Carnivora), free lactose was found to be a minor constituent among a variety of neutral and acidic oligosaccharides, which predominated over lactose. The milk oligosaccharides were isolated from the carbohydrate fractions of each of four samples of raccoon milk and their chemical structures determined by ¹H-NMR and MALDI-TOF mass spectroscopies. The structures of the four neutral milk oligosaccharides were Fuc(α1-2)Gal(β1-4)Glc (2'-fucosyllactose), Fuc(α1-2)Gal(β1-4)GlcNAc(β1-3)Gal(β1-4)Glc (lacto-N-fucopentaose IV), Fuc(α1-2)Gal(β1-4)GlcNAc(β1-3)Gal(β1-4)GlcNAc(β1-3)Gal(β1-4)Glc (fucosyl para lacto-N-neohexaose) and Fuc(α1-2)Gal(β1-4)GlcNAc(β1-3)[Fuc(α1-2)Gal(β1-4)GlcNAc(β1-6)]Gal(β1-4)Glc (difucosyl lacto-N-neohexaose). No type I oligosaccharides, which contain Gal(β1-3)GlcNAc units, were detected, but type 2 saccharides, which contain Gal(β1-4)GlcNAc units were present. The monosaccharide compositions of two of the acidic oligosaccharides were [Neu5Ac]₁[Hex]₆[HexNAc]₄[deoxy Hex]₂, while those of another two were [Neu5Ac]₁[Hex]₈[HexNAc]₆[deoxy Hex]_3. These acidic oligosaccharides contained α(2-3) or α(2-6) linked Neu5Ac, non reducing α(1-2) linked Fuc, poly N-acetyllactosamine (Gal(β1-4)GlcNAc) and reducing lactose.

Keywords: Carnivora; Milk oligosaccharides; Procyon lotor; Raccoon milk; Raccoon milk oligosaccharides.