STUDIES ON BIOSYNTHESIS OF DNA POLYMERASE OF RAT LIVER MITOCHONDRIA
STUDIES ON BIOSYNTHESIS OF DNA POLYMERASE OF RAT LIVER MITOCHONDRIA
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DOI：
10.1016/0003-9861(69)90485-8
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发表时间：
1969-01-01
影响因子：
3.9
通讯作者：
KALF, GF
中科院分区：
文献类型：
--
作者：
CHIH, JJ;KALF, GF
用同位素掺入法研究了线粒体DNA聚合酶的生物合成，用~（14）C-亮氨酸或~（14）C-混合氨基酸孵育线粒体DNA聚合酶。显示在线粒体的残余部分从酶分离的膜中含有接近整个线粒体比活性的放射性水平。体内进行的动力学研究表明，亮氨酸被迅速掺入线粒体的残余部分中，并且在短至2分钟的时间内具有几乎等于整个线粒体的比活性。部分纯化的酶掺入放射性更慢，只有在暴露于3 H-亮氨酸60分钟后，酶才具有与整个线粒体相同的比放射性。此外，在酶中观察到的放射性的掺入后60分钟被阻止由事先注射放线菌酮，微粒体incorporation.These结果的抑制剂暂时支持的假设，即线粒体DNA聚合酶，像cytochromec，可能会合成extraperitoneally和运输到细胞器。
The biosynthesis of mitochondrial DNA polymerase was studied by determining the extent of isotope incorporated into the partially purified enzyme which had been isolated from mitochondria labeled in bothin vivoandin vitroexperiments.The DNA polymerase, isolated from mitochondria incubated with14C-leucine or14C-mixedl-amino acidsin vitro, showed no incorporation of radioactivity under conditions where the residue fraction of mitochondria (membranes) from the enzyme isolation contained a level of radioactivity which approached the specific activity of whole mitochondria.Kinetic studies carried outin vivoshowed that3H-leucine was rapidly incorporated into the residue fraction of mitochondria and at time periods as short as 2 min, had a specific activity almost equal to that of whole mitochondria. The partially purified enzyme incorporated radioactivity more slowly and only after 60 min exposure to the3H-leucine did the enzyme have a specific radioactivity equal to that of whole mitochondria. Moreover, the incorporation of radioactivity observed in the enzyme after 60 min was prevented by the prior injection of cycloheximide, an inhibitor of microsomal incorporation.These results tentatively support the hypothesis that mitochondrial DNA polymerase, like cytochromec, may be synthesized extramitochondrially and transported into the organelle.