根据14CO2数据评估磷酸戊糖途径。经典方程应用于非均匀组织时的易错性。
Evaluation of the pentose phosphate pathway from 14CO2 data. Fallibility of a classic equation when applied to non-homogeneous tissues.
作者信息
Larrabee M G
机构信息
Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218.
出版信息
Biochem J. 1990 Nov 15;272(1):127-32. doi: 10.1042/bj2720127.
A classic equation that has frequently been used to estimate the fraction of glucose metabolized by the pentose phosphate pathway, using 14CO2 data, is more simply re-derived with careful consideration of the assumptions involved and the conditions under which it is applicable. The equation is shown to be unreliable for non-homogeneous tissues, depending on the fraction of triose phosphate converted to CO2. The formula in question is as follows: ([1]CO2/G-[6]CO2/G)/(1-[6]CO2/G) = 3Fmet./(1 + 2Fmet.) where [1]CO2 and [6]CO2 are output rates of carbons 1 and 6 of glucose respectively to CO2, G is the rate of glucose uptake and Fmet. is the fraction of the glucose that is metabolized to CO2 and triose phosphate by the pentose phosphate pathway, allowing for recycling of an appropriate fraction of the fructose-6-phosphate produced by the pathway. This analysis illustrates the importance of suitably testing any equation that assumes homogeneity before application to non-homogeneous tissues.
一个经典方程常被用于利用(^{14}CO_2)数据估算通过磷酸戊糖途径代谢的葡萄糖比例，经过对所涉及假设及适用条件的仔细考量，可以更简便地重新推导该方程。结果表明，对于非均匀组织，该方程不可靠，这取决于磷酸丙糖转化为(CO_2)的比例。所讨论的公式如下：(([1]CO_2/G - [6]CO_2/G)/(1 - [6]CO_2/G) = 3F_{met.}/(1 + 2F_{met.}))，其中([1]CO_2)和([6]CO_2)分别是葡萄糖的碳1和碳6输出到(CO_2)的速率，(G)是葡萄糖摄取速率，(F_{met.})是通过磷酸戊糖途径代谢为(CO_2)和磷酸丙糖的葡萄糖比例，同时考虑了该途径产生的果糖-6-磷酸适当比例的循环利用。该分析说明了在应用于非均匀组织之前，对任何假设均匀性的方程进行适当测试的重要性。
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