CHARACTERIZATION OF 2 DISTINCT ALLYL PYROPHOSPHATASE ACTIVITIES FROM RAT-LIVER MICROSOMES
CHARACTERIZATION OF 2 DISTINCT ALLYL PYROPHOSPHATASE ACTIVITIES FROM RAT-LIVER MICROSOMES
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DOI：
10.1006/abbi.1994.1516
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发表时间：
1994-12-01
影响因子：
3.9
通讯作者：
VAIDYA, S
中科院分区：
文献类型：
--
作者：
BANSAL, VS;VAIDYA, S
我们已经确定和特点两个新的烯丙基焦磷酸酶活性从大鼠肝微粒体。一种特异性地将焦磷酸法呢酯（FPP）水解为法呢醇，另一种将焦磷酸香叶基香叶基酯（GGPP）转化为香叶基香叶醇。因此，我们将它们分别命名为法尼基焦磷酸酶（FPPase）和香叶基香叶基焦磷酸酶（GGPPase）活性。其它焦磷酸烯丙酯，即，异戊烯基焦磷酸、二甲基烯丙基焦磷酸和香叶基焦磷酸不作为这些活性的底物。这两种活性都不依赖于金属离子，并表现出酸性pH最适值（5.5和6.0）。微粒体FPPase对FPP的Km为7 μ M，在pH 5.5时的比活性为6.8 nmol/min/mg蛋白质。GGPP是一种有效的FPPase非竞争性抑制剂。FPP对GGPPase活性无抑制作用。微粒体GGPP酶对GGPP的Km为12 μ M，比活性为14 nmol/min/mg蛋白质。FPP酶活性的Km值随pH值的增加而增加。GGPPase活性随pH值的增加而不受影响。金属离子Zn ~（2+）和Mn ~（2+）是GGPPase活性的有效抑制剂。与角鲨烯合酶相比，萨拉戈萨酸B是FPPase/GGPPase活性的弱抑制剂。与FPPase（5 μ M）相比，GGPPase活性以高四倍的IC 50（20 μ M）被抑制。因此，可以通过萨拉戈萨酸B抑制来区分FPPP酶和GGPPP酶活性。动力学分析进一步表明，Zaragozic acid B是一种混合型非竞争性抑制剂。(C)1994年出版社出版。
We have identified and characterized two novel allyl pyrophosphatase activities from rat liver microsomes. One specifically hydrolyzes farnesyl pyrophosphate (FPP) to farnesol and the other converts geranylgeranyl pyrophosphate (GGPP) to geranylgeranol. Hence, we named them farnesyl pyrophosphatase (FPPase) and geranylgeranyl pyrophosphatase (GGPPase) activities, respectively. Other allyl pyrophosphates, i.e., isopentenyl pyrophosphate, dimethyl allyl pyrophosphate, and geranyl pyrophosphate, did not act as substrates for these activities. Both activities are metal ion independent and exhibit acidic pH optima (5.5 and 6.0). Microsomal FPPase has a K-m for FPP of 7 mu M and a specific activity of 6.8 nmol/min/mg protein at pH 5.5. GGPP is a potent noncompetitive inhibitor of FPPase. FPP has no inhibitory effect on GGPPase activity. Microsomal GGPPase has a K-m for GGPP of 12 mu M and a specific activity of 14 nmol/min/mg protein. The K-m of FPPase activity for FPP increases with an increase in pH. The GGPPase activity remains unaffected with an increase in pH. Metal ions Zn2+ and Mn2+ are potent inhibitors of GGPPase activity. Zaragozic acid B is a weak inhibitor of FPPase/GGPPase activities as compared to squalene synthase. GGPPase activity is inhibited with a fourfold higher IC50 (20 mu M) as compared to FPPase (5 mu M). Hence, the FPPase and GGPPase activities can be differentiated by zaragozic acid B inhibition. Kinetic analysis of inhibition of FPPase by zaragozic acid B further indicates that it is a mixed type noncompetitive inhibitor. (C) 1994 Academic Press, Inc.