仓鼠黑素瘤中糜蛋白酶对黑素体酪氨酸酶的激活作用
Chymotrypsin activation of melanosome tyrosinase in hamster melanotic melanoma.
作者信息
Blagoeva P M, Pandov H I, Stoichkova N I
出版信息
J Cancer Res Clin Oncol. 1979 Oct;95(2):139-45. doi: 10.1007/BF00401008.
The tyrosinase activity in two sucrose gradient isolated melanosome fractions from a melanotic hamster melanoma was found to increase after alpha-chymotrypsin treatment. The enhancement in tyrosinase activity had its maximum at a concentration of 1 mg/ml alpha-chymotrypsin after 120 min incubation at 37 degrees C. No direct activating effect of alpha-chymotrypsin was found either on the soluble tyrosinase fraction from freshly prepared untreaed whole-tumor homogenate or on purified mushroom tyrosinase. The activating effect of alpha-chymotrypsin upon the melanosome tyrosinase is believed to be due to the endopeptidic hydrolysis of the--CO--NH--bound existing between tyrosinase and tyrosine and phenylalanine residues in the melanin molecule. Although alternative interpretations are not excluded, the observed enhancement in tyrosinase activity after alpha-chymotrypsin treatment of melanosomes might indicate the existence of an "enzyme liberating" mechanism in the melanosomes.
在一只患黑素瘤的仓鼠的黑色素瘤中，从两个经蔗糖梯度分离的黑素体组分中发现，α-胰凝乳蛋白酶处理后酪氨酸酶活性增加。在37℃孵育120分钟后，当α-胰凝乳蛋白酶浓度为1mg/ml时，酪氨酸酶活性增强达到最大值。未发现α-胰凝乳蛋白酶对新鲜制备的未经处理的全肿瘤匀浆中的可溶性酪氨酸酶组分或纯化的蘑菇酪氨酸酶有直接激活作用。α-胰凝乳蛋白酶对黑素体酪氨酸酶的激活作用被认为是由于黑色素分子中酪氨酸酶与酪氨酸和苯丙氨酸残基之间存在的肽键发生了内肽酶水解。尽管不排除其他解释，但α-胰凝乳蛋白酶处理黑素体后观察到的酪氨酸酶活性增强可能表明黑素体中存在一种“酶释放”机制。
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