Tewari Y B, Steckler D K, Goldberg R N
Chemical Thermodynamics Division, National Bureau of Standards, Gaithersburg, Maryland 20899.
J Biol Chem. 1988 Mar 15;263(8):3664-9.
Thermodynamics of isomerization reactions involving sugar phosphates have been studied using heat-conduction microcalorimetry. For the process glucose 6-phosphate2-(aqueous) = fructose 6-phosphate2- (aqueous), K = 0.285 +/- 0.004, delta Go = 3.11 +/- 0.04 kJ.mol-1, delta Ho = 11.7 +/- 0.2 kJ.mol-1, and delta Cop = 44 +/- 11 J.mol-1.K-1 at 298.15 K. For the process mannose 6-phosphate2- (aqueous) = fructose 6-phosphate2- (aqueous), K = 0.99 +/- 0.05, delta Go = 0.025 +/- 0.13 kJ.mol-1, delta Ho = 8.46 +/- 0.2 kJ.mol-1, and delta Cop = 38 +/- 25 J.mol-1.K-1 at 298.15 K. The standard state is the hypothetical ideal solution of unit molality. An approximate result (-14 +/- 5 kJ.mol-1) was obtained for the enthalpy of isomerization of ribulose 5-phosphate (aqueous) to ribose 5-phosphate (aqueous). The data from the literature on isomerization reactions involving sugar phosphates have been summarized, adjusted to a common reference state, and examined for trends and relationships to each other and to other thermodynamic measurements. Estimates are made for thermochemical parameters to predict the state of equilibrium of the several isomerizations considered herein.
利用热传导微量热法研究了涉及磷酸糖的异构化反应的热力学。对于磷酸葡萄糖6 -（水溶液）=磷酸果糖6 -（水溶液）这一过程，在298.15 K时，K = 0.285±0.004，ΔGo = 3.11±0.04 kJ·mol-1，ΔHo = 11.7±0.2 kJ·mol-1，以及ΔCop = 44±11 J·mol-1·K-1。对于磷酸甘露糖6 -（水溶液）=磷酸果糖6 -（水溶液）这一过程，在298.15 K时，K = 0.99±0.05，ΔGo = 0.025±0.13 kJ·mol-1，ΔHo = 8.46±0.2 kJ·mol-1，以及ΔCop = 38±25 J·mol-1·K-1。标准态是假设的单位质量摩尔浓度的理想溶液。对于磷酸核酮糖5 -（水溶液）异构化为磷酸核糖5 -（水溶液）的焓，得到了一个近似结果（-14±5 kJ·mol-1）。对文献中涉及磷酸糖的异构化反应的数据进行了总结，将其调整到一个共同的参考态，并研究了它们之间的趋势和相互关系以及与其他热力学测量值的关系。对热化学参数进行了估算，以预测本文所考虑的几种异构化反应的平衡状态。
