对Busycon canaliculatum二聚体肌红蛋白的配体结合平衡和动力学测量以及多种非协同血红素蛋白的比较配体结合

Ligand binding equilibrium and kinetic measurements on the dimeric myoglobin of Busycon canaliculatum and the comparative ligand binding of diverse non-cooperative heme proteins.

作者信息

Schreiber J K, Parkhurst L J

出版信息

Comp Biochem Physiol A Comp Physiol. 1984;78(1):129-35. doi: 10.1016/0300-9629(84)90104-x.

Abstract

The rate constants and delta H degrees for the non-cooperative dimeric Busycon myoglobin are: oxygen, k' = 4.75 X 10(7) M-1 sec-1, k = 71 sec-1, and CO, l'= 3.46 X 10(5) M-1 sec-1, l = 0.0052 sec-1 at 20 degrees C, pH 7, delta H degrees = -3 kcal/mol for O2 and CO.2. Log-log plots of k vs K for oxygen and of l' vs L for CO binding for numerous non-cooperative hemoglobins and myoglobins point to a large steric influence of the protein on heme ligation reactions. Many of the proteins behave as "R" state for one ligand, but "T" for the other.

摘要

非协同二聚体Busycon肌红蛋白的速率常数和ΔH°如下：对于氧气，k' = 4.75×10⁷ M⁻¹ s⁻¹，k = 71 s⁻¹；对于一氧化碳，l' = 3.46×10⁵ M⁻¹ s⁻¹，l = 0.0052 s⁻¹，在20℃、pH 7条件下，氧气和一氧化碳的ΔH° = -3 kcal/mol。许多非协同血红蛋白和肌红蛋白的氧气结合中k与K的对数-对数图以及一氧化碳结合中l'与L的对数-对数图表明，蛋白质对血红素连接反应有很大的空间影响。许多蛋白质对一种配体表现为“R”态，但对另一种配体表现为“T”态。