Alberty Robert A
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Biophys Chem. 2003 May 1;104(1):327-34. doi: 10.1016/s0301-4622(02)00390-3.
The best way to store data on apparent equilibrium constants for enzyme-catalyzed reactions is to calculate the standard Gibbs energies of formation of the species involved at 298.15 K and zero ionic strength so that equilibrium constants can be calculated at the desired pH and ionic strength. These calculations are described for CoA, acetyl-CoA, oxalyl-CoA, succinyl-CoA, methylmalonyl-CoA, malyl-CoA and CoA-glutathione. The species properties are then used to calculate standard transformed Gibbs energies of formation for these reactants as functions of pH at ionic strength 0.25 M. The species data also make it possible to calculate apparent equilibrium constants of 23 enzyme-catalyzed reactions as a function of pH, including some that cannot be determined directly because they are so large.
存储酶催化反应表观平衡常数数据的最佳方法是计算298.15 K和零离子强度下所涉及物种的标准吉布斯生成能,以便能够在所需的pH值和离子强度下计算平衡常数。本文针对辅酶A、乙酰辅酶A、草酰辅酶A、琥珀酰辅酶A、甲基丙二酰辅酶A、苹果酰辅酶A和辅酶A - 谷胱甘肽进行了这些计算。然后利用这些物种性质计算在离子强度为0.25 M时这些反应物作为pH函数的标准转化吉布斯生成能。这些物种数据还使得计算23种酶催化反应的表观平衡常数作为pH的函数成为可能,其中包括一些由于数值太大而无法直接测定的反应。