Zera A J
Biochem Genet. 1987 Apr;25(3-4):205-23. doi: 10.1007/BF00499314.
Inhibition of phosphoglucose isomerase (PGI) allozymes from the wing-polymorphic waterstrider, Limnoporus canaliculatus, by three pentose-shunt metabolites was studied at several different temperatures. This was done to determine if the allozymes exhibited a differential ability to participate in lipid biosynthesis via differential partitioning of carbon flux through the pentose shunt versus glycolysis. 6-Phosphogluconate and erythrose-4-phosphate proved to be strong competitive inhibitors of PGI, while sedoheptulose-7-phosphate was a very weak inhibitor. The PGI allozymes from L. canaliculatus were differentially inhibited by 6-phosphogluconate at two of the three temperatures studied. However, this property does not appear to be an adaptive difference between the allozymes but, rather, a correlated effect resulting from variation in substrate binding. Estimates of reaction rates for the allozymes indicate that the differences in inhibition result in no detectable differences in reaction velocities. Thus, no evidence in support of the hypothesis that PGI allozymes from Limnoporus canaliculatus were adapted to function in different metabolic capacities via differential inhibition was obtained in this study. However, the importance of this characteristic in allozymic adaptation in natural populations remains an open question.
研究了在几个不同温度下，三种戊糖磷酸途径代谢物对具有翅多态性的水黾Limnoporus canaliculatus的磷酸葡萄糖异构酶（PGI）同工酶的抑制作用。这样做是为了确定这些同工酶是否通过戊糖磷酸途径与糖酵解之间碳通量的差异分配，表现出参与脂质生物合成的不同能力。6-磷酸葡萄糖酸和4-磷酸赤藓糖被证明是PGI的强竞争性抑制剂，而7-磷酸景天庚酮糖是一种非常弱的抑制剂。在所研究的三个温度中的两个温度下，来自Limnoporus canaliculatus的PGI同工酶受到6-磷酸葡萄糖酸的差异抑制。然而，这种特性似乎不是同工酶之间的适应性差异，而是由底物结合变化导致的相关效应。对同工酶反应速率的估计表明，抑制作用的差异并未导致反应速度出现可检测到的差异。因此，在本研究中未获得支持Limnoporus canaliculatus的PGI同工酶通过差异抑制适应不同代谢能力这一假设的证据。然而，这一特性在自然种群的同工酶适应中的重要性仍然是一个悬而未决的问题。
