Allozymes of glucose-6-phosphate isomerase differentially modulate pentose-shunt metabolism in the sea anemone Metridium senile.
Allozymes of glucose-6-phosphate isomerase differentially modulate pentose-shunt metabolism in the sea anemone Metridium senile.
复制标题
葡萄糖-6-磷酸异构酶的同种酶差异调节海葵 Metridium senile 中的戊糖分流代谢。
DOI：
10.1073/pnas.86.8.2737
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发表时间：
1989
影响因子：
11.1
通讯作者：
Hoffmann,RJ
中科院分区：
文献类型：
--
作者：
Zamer,WE;Hoffmann,RJ
We tested the hypothesis that kinetic differences among allelic variants of glucose-6-phosphate isomerase (GPI; D-glucose-6-phosphate ketol-isomerase, EC 5.3.1.9) from the sea anemone Metridium senile differentially modulate glucose metabolism at the glycolysis-pentose-shunt branch point. Fractional contribution of pentose shunt and absolute flux of glucose in glycolysis were measured in fasted or fed anemones acclimated to 5 degrees C or 15 degrees C. When fed, anemones of genotype Gpiss routed a greater fraction of glucose through the shunt than did Gpiff anemones; the effect was more pronounced at 5 degrees C than at 15 degrees C. This confirms predictions from kinetic and population data and is consistent with thermal selection maintaining the variation. Relative levels of shunt metabolism increased at 5 degrees C, compared with 15 degrees C, in fed anemones regardless of genotype, but the proportion of glucose metabolized by the pentose shunt was unchanged by temperature in fasted anemones. Glucose flux through the shunt was constant at approximately 5 pmol.mg-1.hr-1 in fed anemones at 5 degrees C and 15 degrees C and in fasted anemones at 15 degrees C, indicating apparently near-perfect thermal acclimation of the absolute flux of glucose through the shunt in fed, but not in fasted, anemones. Rates of glucose oxidation and flux through the shunt in freshly collected anemones were similar to those of anemones fed and acclimated at 15 degrees C in the laboratory. If these differences affect organismal-level processes, Gpi variation could contribute to Darwinian fitness in thermally varying environments.
