小鼠精子中支链2-羟基酸/2-氧代酸穿梭系统的特性
Properties of the branched-chain 2-hydroxy acid/2-oxo acid shuttle in mouse spermatozoa.
作者信息
Coronel C E, Gallina F G, Gerez de Burgos N M, Burgos C, Blanco A
出版信息
Biochem J. 1986 May 1;235(3):853-8. doi: 10.1042/bj2350853.
Operation of the branched-chain 2-hydroxy acid/2-oxo acid shuttle for the transfer of reducing equivalents in mitochondria of mouse spermatozoa was studied in vitro in reconstituted systems. Results show that the branched-chain 2-oxo acids within the mitochondria are offered several metabolic pathways. (a) Decarboxylation: mouse sperm mitochondria possess high branched-chain 2-oxo acid decarboxylase activity. (b) Recycling to the cytosol by using a transport system which can be inhibited by alpha-cyano-3-hydroxycinnamate and pH 6.8. (c) Transamination to the corresponding amino acids: experiments presented indicate that leucine formed from 4-methyl-2-oxopentanoate may pass to the external phase, re-initiating the cycle. These two last possibilities would allow autocatalytic operation of the shuttle. The branched-chain 2-hydroxy acids apparently do not utilize the monocarboxylate carrier to penetrate the mitochondria.
在体外重组系统中研究了小鼠精子线粒体内用于还原当量转移的支链2-羟基酸/2-氧代酸穿梭机制的运作。结果表明，线粒体内的支链2-氧代酸有几种代谢途径。（a）脱羧作用：小鼠精子线粒体具有高支链2-氧代酸脱羧酶活性。（b）通过一种可被α-氰基-3-羟基肉桂酸和pH 6.8抑制的转运系统循环回到细胞质。（c）转氨生成相应的氨基酸：所展示的实验表明，由4-甲基-2-氧代戊酸形成的亮氨酸可能进入外相，重新启动循环。最后这两种可能性将允许穿梭机制的自动催化运作。支链2-羟基酸显然不利用单羧酸载体穿透线粒体。
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