SYNTHESIS AND DEGRADATION OF TYROSINASE IN CULTURED MELANOMA-CELLS
SYNTHESIS AND DEGRADATION OF TYROSINASE IN CULTURED MELANOMA-CELLS
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DOI：
10.1002/jcp.1041040206
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发表时间：
1980-01-01
影响因子：
5.6
通讯作者：
OIKAWA, A
中科院分区：
文献类型：
--
作者：
SAEKI, H;OIKAWA, A
培养的 B-16 小鼠黑色素瘤细胞 (C2M) 在稳定期的酪氨酸酶 (EC 1.14.18.1) 活性取决于培养基中是否含有葡萄糖或半乳糖。含有半乳糖的培养基中的活性为.apprx。是 pH 7.2 含葡萄糖培养基中的 10 倍。酪氨酸酶活性的这种差异显然是由于酶的合成和降解之间的平衡发生了变化。在存在和不存在环己酰胺的情况下用稳定期培养物进行实验。处于稳定期的黑色素瘤细胞在含有葡萄糖的培养基中不合成酪氨酸酶。当在相同条件下培养时，除了葡萄糖被半乳糖取代外，它们合成了酪氨酸酶。在pH 6.3的含有半乳糖的培养基中的合成速率是在pH 7左右的相同培养基中的1/3，其中酪氨酸酶的比活性每天增加约1/3。 30 纳摩尔/毫克细胞蛋白/小时。酶的降解速率在含有葡萄糖的培养基中实际上与在含有半乳糖的培养基中相同，并且很大程度上取决于培养基的pH。在 pH 6.3 时，半衰期为 .apprx。 pH 7.2 时的 1/3，约为 .apprx。 1.8天。铵盐大大降低了酸性 pH 值下的降解，并受到蛋白酶抑制剂亮肽素的强烈抑制。
The tyrosinase (EC 1.14.18.1) activity of cultured B-16 mouse melanoma cells (C2M) in the stationary phase depends on whether the medium contains glucose or galactose. The activity in medium containing galactose was .apprx. 10 times that in medium containing glucose at pH 7.2. This difference in tyrosinase activity was apparently due to a shift of balance between synthesis and degradation of the enzyme. Experiments were conducted with stationary phase cultures in the presence and absence of cyclohexamide. Melanoma cells in the stationary phase did not synthesize tyrosinase in medium containing glucose. When cultured under identical conditions, except that glucose was replaced by galactose, they synthesized tyrosinase. The rate of synthesis in medium containing galactose at pH 6.3 was 1/3 of that in the same medium at about pH 7, in which the increase in specific activity of tyrosinase per day was .apprx. 30 nmoles/mg cell protein/h. The rate of degradation of the enzyme was practically the same in medium containing glucose as in medium containing galactose, and largely depended on the pH of the culture medium. At pH 6.3, the half-life was .apprx. 1/3 of that at pH 7.2, where it was .apprx. 1.8 days. The degradation at acidic pH values was much reduced by ammonium salt and was strongly inhibited by the protease inhibitor, leupeptin.