Chymotrypsin activates cardiac mitochondrial carnitine-acylcarnitine translocase.
Chymotrypsin activates cardiac mitochondrial carnitine-acylcarnitine translocase.
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胰凝乳蛋白酶激活心脏线粒体肉碱-酰基肉碱转位酶。
DOI：
10.1042/bj2610363
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发表时间：
1989
期刊：
影响因子：
--
通讯作者：
McMillin,JB
中科院分区：
文献类型：
--
作者：
Wolkowicz,PE;Pauly,DF;VanWinkle,WB;McMillin,JB
肉碱-酰基肉碱转位酶促进肉碱和酰基肉碱在β-氧化过程中转运到线粒体基质中。我们的结果表明，胰凝乳蛋白酶可以将 N-乙基马来酰亚胺 (NEM) 敏感的肉碱或棕榈酰肉碱交换的最大速度激活 7 倍，同时使转位酶对肉碱的亲和力加倍。胰凝乳蛋白酶的激活严格依赖于蛋白水解介质中游离或短链酰基肉碱的存在，激活程度随着蛋白水解介质中酰基肉碱链长度的增加而降低。仅在产生转位酶激活的条件下，胰凝乳蛋白酶处理会降低 NEM 抑制转位酶的表观 I50 值（产生半最大抑制所需的抑制剂浓度）。胰凝乳蛋白酶对软骨下颗粒膜的修饰不会导致总体超微结构变化或这些膜对肉毒碱的被动渗透性增加。数据表明，肉碱结合会产生易位酶构象的变化，从而允许胰凝乳蛋白酶修饰发生。这种修饰改变了转位酶的动力学和抑制剂结合特性。
The carnitine-acylcarnitine translocase facilitates carnitine and acylcarnitine transport into the mitochondrial matrix during beta-oxidation. Our results demonstrate that chymotrypsin can activate the maximal velocity of N-ethylmaleimide (NEM)-sensitive carnitine or palmitoylcarnitine exchange 7-fold, while doubling the affinity of the translocase for carnitine. Chymotrypsin activation is strictly dependent on the presence of free or short-chain acylcarnitine in the proteolysis medium, the extent of activation decreasing as the acylcarnitine chain length in the proteolysis medium increases. Chymotrypsin treatment decreases the apparent I50 value (inhibitor concentration required to give half-maximal inhibition) of the translocase for inhibition by NEM only under conditions which produce translocase activation. Modification of submitochondrial particle membranes by chymotrypsin does not result in gross ultrastructural changes or in an increase in the passive permeability of these membranes to carnitine. The data suggest that carnitine binding produces a change in translocase conformation which allows chymotrypsin modification to occur. This modification alters the kinetic and inhibitor-binding properties of the translocase.