牛奶和乳腺核糖核酸酶活性的物种差异。

Species differences in ribonuclease activity of milk and mammary gland.

Liu D K, Williams G H

Comp Biochem Physiol B. 1982;71(3):535-8. doi: 10.1016/0305-0491(82)90424-2.

Abstract

Ribonuclease (RNAase) activity in milk of mouse, rat, rabbit, dog, goat, cow and human and in mammary tissue of mouse and rat has been determined at pH 7.4 under various ionic conditions. 2. RNAase in milk of rabbit, cow, goat, human, dog and mouse exhibited no strong ionic preference while activity of rat milk RNAase was greatly enhanced by Ca2+. Enzyme from every source preferred pyrimidine over purine homopolymers as substrate. 3. Comparing the maximal activity per ml found for each species, milk of rabbit, rat and cow had the highest activity, that of human and goat was intermediate and that of dog and mouse was the lowest. Differences between strains were smaller than interspecific differences. 4. In rat and mouse, milk RNAase activity is a function of mammary RNAase activity in the gland.

摘要

已在不同离子条件下于pH 7.4测定了小鼠、大鼠、兔、狗、山羊、奶牛和人类乳汁以及小鼠和大鼠乳腺组织中的核糖核酸酶（RNAase）活性。2. 兔、奶牛、山羊、人类、狗和小鼠乳汁中的RNAase没有强烈的离子偏好，而大鼠乳汁RNAase的活性则被Ca2+大大增强。每种来源的酶都更倾向于将嘧啶同聚物而非嘌呤同聚物作为底物。3. 比较每个物种每毫升乳汁的最大活性，兔、大鼠和奶牛的乳汁活性最高，人类和山羊的居中，狗和小鼠的最低。品系间的差异小于种间差异。4. 在大鼠和小鼠中，乳汁RNAase活性是腺体中乳腺RNAase活性的函数。