钙和锶与牛α-乳白蛋白结合的热力学

Thermodynamics of the binding of calcium and strontium to bovine alpha-lactalbumin.

作者信息

Schaer J J, Milos M, Cox J A

出版信息

FEBS Lett. 1985 Oct 7;190(1):77-80. doi: 10.1016/0014-5793(85)80431-2.

Abstract

Microcalorimetry and equilibrium gel filtration were used to determine the thermodynamic functions delta H degrees, delta G degrees and delta S degrees guiding the interaction of Ca2+ and Sr2+ with bovine alpha-lactalbumin. Two methods of nearly complete metal removal from the protein gave identical results. The single Ca- and Sr-binding site, which has moderate affinity for these ions (KCa = 2.5 X 10(6) M-1 and KSr = 5.1 X 10(5) M-1), displays unusually large enthalpy changes of -118 kJ X mol-1 for Ca2+ and -75 kJ X mol-1 for Sr2+. The concomitant reaction entropies equal -273 and -142 J X K-1 X mol-1, respectively.

摘要

微量量热法和平衡凝胶过滤法被用于测定指导Ca2+和Sr2+与牛α-乳白蛋白相互作用的热力学函数ΔH°、ΔG°和ΔS°。从蛋白质中几乎完全去除金属的两种方法给出了相同的结果。对这些离子具有中等亲和力的单一Ca和Sr结合位点（KCa = 2.5×10(6) M-1和KSr = 5.1×10(5) M-1），对于Ca2+显示出异常大的焓变-118 kJ·mol-1，对于Sr2+为-75 kJ·mol-1。伴随的反应熵分别等于-273和-142 J·K-1·mol-1。