Identification of N-acetyl-4-O-acetylneuraminyl-lactose in Echidna milk.
The identity of a novel form of sialyl-lactose found in milk of the echidna (Tachyglossus aculeatus) was investigated. The sialyl-lactose yielded equimolar amounts of N-acetylneuraminic acid and lactose during mild acid hydrolysis but was resistant to the action of a bacterial neuraminidase. A viral neuraminidase hydrolysed it to lactose plus a form of sialic acid that reacted positively with thiobarbituric acid reagent but whose chromatographic mobility was greater than that of N-acetylneuraminic acid. Treatment with alkali converted the sialyl-lactose into a substance with the same chromatographic mobility as N-acetylneuraminyl-(2-->3)-lactose and made it susceptible to the action of bacterial neuraminidase. The sialyl-lactose contained one mol of ester (identified as acetyl), and released one mol of formaldehyde during periodate oxidation, per mol of sialic acid. It did not contain N-glycollylneuraminic acid. These results indicate that the sialyl-lactose is N-acetyl-4-O-acetylneuraminyl-(2-->3)-lactose. Echidna milk contained, in addition, a small amount of N-acetylneuraminyl-(2-->3)-lactose.
D000818:Animals; D002850:Chromatography, Gel; D002854:Chromatography, Paper; D005260:Female; D005557:Formaldehyde; D006016:Glycolates / Q000032:analysis; D006868:Hydrolysis; D007785:Lactose / Q000302:isolation & purification; D008892:Milk / Q000032:analysis*; D008968:Molecular Conformation; D009007:Monotremata; D009439:Neuraminidase; D009844:Oligosaccharides / Q000302:isolation & purification*; D010504:Periodic Acid; D012794:Sialic Acids / Q000302:isolation & purification*
D006016:Glycolates; D009844:Oligosaccharides; D012794:Sialic Acids; D010504:Periodic Acid; D005557:Formaldehyde; D009439:Neuraminidase; D007785:Lactose