Precious W Y, Barrett J
Department of Biological Sciences, University College of Wales, Aberystwyth, Dyfed, United Kingdom.
Biochem Cell Biol. 1993 Jul-Aug;71(7-8):315-23. doi: 10.1139/o93-048.
The elasticities for the different steps of carbohydrate catabolism in the tapeworm Hymenolepis diminuta were estimated from perturbation experiments. These data were then used to calculate flux and metabolite control coefficients. Enzyme elasticities were also calculated from the rate equations and an independent estimate of the flux control coefficients for phosphoenolpyruvate carboxykinase was made by inhibitor titration. The values obtained for the flux control coefficients for carbohydrate breakdown in H. diminuta are consistent with how the pathway is thought to be controlled in vivo. A sensitivity analysis of the flux control coefficients of the important regulatory enzymes in the pathway shows that for hexokinase, phosphofructokinase, pyruvate kinase, and phosphoenolpyruvate carboxykinase there are three or four key elasticities which have a significant effect on the coefficient. For glycogen synthase, the major factor in determining the magnitude of the flux control coefficient is the relative flux through the branch.
通过微扰实验估算了微小膜壳绦虫碳水化合物分解代谢不同步骤的弹性。然后利用这些数据计算通量和代谢物控制系数。还从速率方程计算了酶弹性，并通过抑制剂滴定对磷酸烯醇式丙酮酸羧激酶的通量控制系数进行了独立估计。微小膜壳绦虫碳水化合物分解通量控制系数的测定值与该途径在体内的调控方式一致。对该途径中重要调节酶的通量控制系数进行敏感性分析表明，对于己糖激酶、磷酸果糖激酶、丙酮酸激酶和磷酸烯醇式丙酮酸羧激酶，有三到四个关键弹性对系数有显著影响。对于糖原合酶，决定通量控制系数大小的主要因素是通过该分支的相对通量。
