腺苷5'-三磷酸水解为腺苷5'-二磷酸的热力学

Thermodynamics of the hydrolysis of adenosine 5'-triphosphate to adenosine 5'-diphosphate.

作者信息

Gajewski E, Steckler D K, Goldberg R N

出版信息

J Biol Chem. 1986 Sep 25;261(27):12733-7.

Abstract

The enthalpy of hydrolysis of the enzyme-catalyzed (heavy meromyosin) conversion of adenosine 5'-triphosphate (ATP) to adenosine 5'-diphosphate (ADP) and inorganic phosphate has been investigated using heat-conduction microcalorimetry. Enthalpies of reaction were measured as a function of ionic strength (0.05-0.66 mol kg-1), pH (6.4-8.8), and temperature (25-37 degrees C) in Tris/HCl buffer. The measured enthalpies were adjusted for the effects of proton ionization and metal ion binding, protonation and interaction with the Tris buffer, and ionic strength effects to obtain a value of delta H0 = -20.5 +/- 0.4 kJ mol-1 at 25 degrees C for the process, ATP4-(aq) + H2O(l) = ADP3-(aq) + HPO2-4(aq) + H+(aq) where aq is aqueous and l is liquid. Heat measurements carried out at different temperatures lead to a value of delta C0p = -237 +/- 30 J mol-1 K-1 for the above process.

摘要

利用热传导微量量热法研究了在酶（重酶解肌球蛋白）催化下，腺苷5'-三磷酸（ATP）转化为腺苷5'-二磷酸（ADP）和无机磷酸的水解焓。在Tris/HCl缓冲液中，测量了反应焓随离子强度（0.05 - 0.66 mol kg⁻¹）、pH值（6.4 - 8.8）和温度（25 - 37℃）的变化。对测量的焓进行了质子电离和金属离子结合、质子化以及与Tris缓冲液相互作用和离子强度效应的校正，以获得25℃下该过程ATP⁴⁻(aq) + H₂O(l) = ADP³⁻(aq) + HPO₂⁻₄(aq) + H⁺(aq)（其中aq表示水溶液，l表示液体）的ΔH₀ = -20.5 ± 0.4 kJ mol⁻¹值。在不同温度下进行的热测量得出上述过程的ΔC₀p = -237 ± 30 J mol⁻¹ K⁻¹值。