Stewart I M, Messer M, Walcott P J, Gadiel P A, Griffiths M
Aust J Biol Sci. 1983;36(2):139-46. doi: 10.1071/bi9830139.
The activities of various glycosidases in homogenates of the small-intestinal mucosa of one adult and two suckling echidnas, Tachyglossus aculeatus, were investigated. The activities of lactase (beta-D-galactosidase), beta-N-acetylglucosaminidase, neuraminidase and alpha-L-fucosidase were higher in the sucklings than in the adult animal. Maltase and isomaltase activities were lower. Sucrase and cellobiase activities were absent or present in trace amounts only. The lactase activity had a pH optimum of 4.0-4.5, was predominantly in the soluble fraction following ultracentrifugation and was inhibited by p-chloromercuribenzene sulfonate, suggesting that it was due to a lysosomal acid beta-galactosidase and not a brush-border neutral lactase. The maltase activity of the sucklings also had the characteristics predominantly of a lysosomal acid hydrolase. It is proposed that in suckling echidnas, the oligosaccharides (mainly neuraminyllactose and fucosyllactose) of the mother's milk are digested intracellularly by lysosomal enzymes, rather than at the brush border, of the epithelial cells of the small-intestinal mucosa.
对一只成年针鼹和两只乳针鼹（针鼹属）小肠黏膜匀浆中各种糖苷酶的活性进行了研究。与成年动物相比，乳针鼹中乳糖酶（β-D-半乳糖苷酶）、β-N-乙酰氨基葡萄糖苷酶、神经氨酸酶和α-L-岩藻糖苷酶的活性更高。麦芽糖酶和异麦芽糖酶的活性较低。蔗糖酶和纤维二糖酶的活性不存在或仅微量存在。乳糖酶活性的最适pH值为4.0 - 4.5，超速离心后主要存在于可溶部分，并受到对氯汞苯磺酸盐的抑制，这表明它是由溶酶体酸性β-半乳糖苷酶引起的，而不是刷状缘中性乳糖酶。乳针鼹的麦芽糖酶活性也主要具有溶酶体酸性水解酶的特征。有人提出，在乳针鼹中，母乳中的寡糖（主要是神经氨酸乳糖和岩藻糖乳糖）是由小肠黏膜上皮细胞的溶酶体酶在细胞内消化的，而不是在刷状缘消化。
