Messer M
Biochem J. 1974 May;139(2):415-20. doi: 10.1042/bj1390415.
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.
对在针鼹（针鼹属）乳汁中发现的一种新型唾液酸乳糖的结构进行了研究。该唾液酸乳糖在温和酸水解过程中产生等摩尔量的N - 乙酰神经氨酸和乳糖，但对细菌神经氨酸酶的作用具有抗性。一种病毒神经氨酸酶将其水解为乳糖加一种与硫代巴比妥酸试剂呈阳性反应的唾液酸形式，但其色谱迁移率大于N - 乙酰神经氨酸。用碱处理可将该唾液酸乳糖转化为一种与N - 乙酰神经氨酸基 -（2→3）-乳糖具有相同色谱迁移率的物质，并使其易于受到细菌神经氨酸酶的作用。每摩尔唾液酸，该唾液酸乳糖含有一摩尔酯（鉴定为乙酰基），并且在高碘酸盐氧化过程中释放一摩尔甲醛。它不含有N - 糖基神经氨酸。这些结果表明该唾液酸乳糖是N - 乙酰 - 4 - O - 乙酰神经氨酸基 -（2→3）-乳糖。此外，针鼹乳汁还含有少量的N - 乙酰神经氨酸基 -（2→3）-乳糖。
