甲状旁腺激素的代谢。肾脏酶对125I标记激素的降解。
Metabolism of parathyroid hormone. Degradation of 125I-labelled hormone by a kidney enzyme.
作者信息
Martin T J, Melick R A, de Luise M
出版信息
Biochem J. 1969 Feb;111(4):509-14. doi: 10.1042/bj1110509.
A study was made of the enzymic degradation of (125)I-labelled parathyroid hormone by rat kidney microsomes. Incubation with microsomes resulted in rapid destruction of the labelled hormone. The microsomal factor was not separable by dialysis, and the reaction was favoured by pH values in the physiological range. Velocity of the reaction varied directly as the substrate concentration, and additional crude parathyroid hormone (trichloroacetic acid-precipitated, 3.68mg./ml.) inhibited destruction of labelled hormone. There was much less inhibition with added trichloroacetic acid-precipitated calcitonin (3.92mg./ml.) and virtually none with added pig insulin (3.80mg./ml.). Gel filtration of control medium on P6 (Bio-Gel) yielded one radioactive peak at the void volume. After incubation with microsomes three further peaks were obtained on gel filtration. Only the void-volume peak contained intact (125)I-labelled parathyroid hormone, indicating that the microsomal enzyme degraded labelled hormone to a number of smaller fragments.
对大鼠肾微粒体对（125）I标记的甲状旁腺激素的酶促降解进行了研究。与微粒体一起孵育导致标记激素迅速被破坏。微粒体因子不能通过透析分离，并且该反应在生理范围内的pH值下更有利。反应速度与底物浓度成正比，额外添加粗制甲状旁腺激素（经三氯乙酸沉淀，3.68mg/ml）可抑制标记激素的破坏。添加经三氯乙酸沉淀的降钙素（3.92mg/ml）时抑制作用小得多，而添加猪胰岛素（3.80mg/ml）时几乎没有抑制作用。对照培养基在P6（生物凝胶）上进行凝胶过滤，在空体积处产生一个放射性峰。与微粒体孵育后，凝胶过滤得到另外三个峰。只有空体积峰含有完整的（125）I标记的甲状旁腺激素，这表明微粒体酶将标记激素降解为许多较小的片段。
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