Stimulation of Propionyl CoA and β-Methylcrotonyl CoA Carboxylase Activities in Human Leukocytes and Cultured Fibroblasts by Biotin
Stimulation of Propionyl CoA and β-Methylcrotonyl CoA Carboxylase Activities in Human Leukocytes and Cultured Fibroblasts by Biotin
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生物素对人白细胞和培养成纤维细胞中丙酰辅酶A和β-甲基巴豆酰辅酶A羧化酶活性的刺激
DOI：
10.1203/00006450-197911000-00014
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发表时间：
1979
影响因子：
3.6
通讯作者：
L. Rosenberg
中科院分区：
文献类型：
--
作者：
B. Wolf;L. Rosenberg
摘要：一名13个月大的分离性PCC缺乏症女婴，在服用生物素补充剂（4.5 mg/天）6个月后，其外周血白细胞丙酰辅酶a羧化酶（PCC）活性仅为对照组的3%，但其βMCC活性却显著升高，达到对照组活性的20倍。停止补充生物素后，白细胞提取物中的βMCC活性在3周内下降到刚好高于正常范围的值，而PCC活性没有相关变化；再给生物素使她的βMCC活性在3天内上升到最初的升高值。这些结果促使3名正常成人每天口服20毫克生物素后白细胞提取物中PCC和βMCC活性的测定。在7 ~ 10天内，PCC和βMCC活性分别增加了2 ~ 3倍和4 ~ 9倍。停用生物素后，两种酶的活性在4-5周内恢复正常。高浓度生物素和βMCC活性对培养成纤维细胞的影响也进行了研究。在含有胎牛血清和高浓度生物素（900 μg/ml）的培养基中生长的正常成纤维细胞中，PCC活性仅增加11%。在含10%人血清和0.1 ~ 1.0 μg/ml生物素的培养基中培养正常成纤维细胞，PCC和βMCC活性分别提高70 ~ 75%和120 ~ 140%。这种刺激与成纤维细胞的生长周期无关。此外，环己亚胺未能抑制生物素引起的PCC活性的增加，这表明成纤维细胞活性的增强不是由于新生羧化酶的合成。这些研究表明，高浓度的生物素可以刺激人体组织中生物素依赖的羧化酶，可能通过将羧化酶转化为全息羧化酶或激活先前存在的无活性全息羧化酶。推测：高浓度生物素刺激人丙酰辅酶a和β-甲基戊酰辅酶a羧化酶在体内外周血白细胞和培养的皮肤成纤维细胞中的活性，为研究人体内生物素的细胞代谢提供了一个有希望的模型。
Summary: Initially, it was observed that whereas the propionyl CoA carboxylase (PCC) activity in peripheral blood leukocytes of a 13-month-old girl with isolated PCC deficiency who had been given biotin supplements (4.5 mg/day) for 6 months was only 3% of control, her βMCC activity was greatly elevated at 20 times control activity. After biotin supplements were discontinued, βMCC activity in leukocyte extracts declined over 3 wk to values just above the normal range with no associated change in PCC activity; readministration of biotin caused her βMCC activity to rise in 3 days to the initial elevated values. These results prompted measurement of PCC and βMCC activities in leukocyte extracts of three normal adults given 20 mg biotin orally per day. Their PCC and βMCC activities increased 2− to 3-fold and 4− to 9-fold, respectively, within 7–10 days. After biotin was discontinued, both enzyme activities returned to normal in 4–5 wk. The effect of high concentrations of biotin and βMCC activities was also investigated in cultured fibroblasts from three control subjects. PCC activity increased only 11% in normal fibroblasts grown in medium containing fetal bovine serum and high concentrations of biotin (900 μg/ml). However, PCC and βMCC activities were increased 70–75% and 120–140%, respectively, when confluent normal fibroblasts were incubated in medium containing 10% human serum and 0.1–1.0 μg/ml biotin. This stimulation was independent of the fibroblast growth cycle. Furthermore, cycloheximide failed to inhibit the increase in PCC activity caused by biotin, suggesting that the enhanced activity in fibroblasts was not due to de novo carboxylase synthesis. These studies demonstrate that high concentrations of biotin can stimulate biotin-dependent carboxylases in human tissues, possibly by converting apocarboxylase to holocar-boxylase or by activating preexisting inactive holocarboxylase.Speculation: The stimulation of human propionyl CoA and β-methylcrotonyl CoA carboxylase activities in peripheral blood leukocytes in vivo and in cultured skin fibroblasts by high concentrations of biotin represents a promising model for investigating the cellular metabolism of biotin in man.