用过量碘处理的大鼠和豚鼠的甲状腺球蛋白对蛋白水解的敏感性。
Susceptibility to proteolysis of thyroglobulin from rats and guinea-pigs treated with excess iodide.
作者信息
Sinadinović J, Kraincanić M, Marinković B, Jovanović M, Petrović N, Liewendahl K
出版信息
Acta Endocrinol (Copenh). 1982 Feb;99(2):232-8.
The effect of excess iodide on proteolysis of in vivo 125I-labelled thyroglobulin (Tg) from rats and guinea-pigs was investigated in vitro using preparations of thyroid lysosomes and exogenous proteases (Pronase). Lysosomes were obtained by centrifugation of pig thyroid homogenates. This lysosomal preparation induced maximal proteolysis of Tg at pH 3.6 to 4.6 and was stimulated by KCl. Treatment of rats with excess iodide for up to 28 days had no effect on the proteolysis of Tg by lysosomes or Pronase. Decreased resistance of Tg to proteolysis by lysosomes and pronase was observed in guinea-pigs treated with excess iodide for 3 days, whereas Tg from guinea-pigs treated for longer time periods had increased resistance to proteolysis. This difference in the susceptibility to proteolysis of Tg provides an explanation why long-term administration of excess iodide is goitrogenic in guinea-pigs but not in rats.
利用甲状腺溶酶体制剂和外源性蛋白酶（链霉蛋白酶），在体外研究了过量碘化物对大鼠和豚鼠体内¹²⁵I标记甲状腺球蛋白（Tg）蛋白水解的影响。溶酶体通过猪甲状腺匀浆离心获得。这种溶酶体制剂在pH 3.6至4.6时诱导Tg的最大蛋白水解，并受到氯化钾的刺激。用过量碘化物处理大鼠长达28天，对溶酶体或链霉蛋白酶对Tg的蛋白水解没有影响。在用过量碘化物处理3天的豚鼠中，观察到Tg对溶酶体和链霉蛋白酶蛋白水解的抗性降低，而处理较长时间的豚鼠的Tg对蛋白水解的抗性增加。Tg对蛋白水解敏感性的这种差异解释了为什么长期给予过量碘化物在豚鼠中会致甲状腺肿，而在大鼠中则不会。
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