鼠脑红蛋白突变体F106L与氰根的结合作用

构建了鼠脑红蛋白(Mouse neuroglobin)的突变体F106L, 以探求近端残基对脑红蛋白血红素口袋结构的贡献. 通过溶液核磁共振方法研究了外来配体氰根离子与NgbF106L蛋白的结合作用, 结果显示, 此结合存在动力学过程, 并且NgbF106LCN 突变蛋白氰根络合物可以可逆地释放氰根离子, 并使原来的第6配体His64(E7)又结合回到血红素铁上. 研究结果揭示, G5(Phe106)残基对脑红蛋白血红素构象而言较为保守; QM/MM结构优化结果表明, 位于G5 和FG5的近端残基对蛋白结构稳定性具有重要作用, 并可调控外来配体与蛋白作用的配位平衡与热动力学性质.

Ligand Binding Affinity of Cyanide Complex of Single Mutant F106L Murine Met-Neuroglobin

Neuroglobin(Ngb), a recently discovered mammalian heme protein, is predominantly expressed in vertebrate brain and retina. The site G5(F106) in protein structure has been proved as one of the key proximal residues in maintenance of heme pocket conformation. Herein, to investigate the attributions of heme pocket structure of Ngb, especially in proximal side, the mutant F106L was implemented in laboratory. Solution 1H NMR method was utilized to study the binding process of exterior ligand CN- to F106L Ngb mutant. The results indicate that in the binding of CN- with NgbF106L a dynamic process exists and the Ngb F106LCN complex could reversibly release CN-, hence the interior His64 might rebind to iron as the sixth ligand. It reveals that the G5 residue in Ngb serves to conservation in partial conformation of heme pocket predominantly. Furthermore, molecular mechanics calculation suggests that proximal residues like G5 and FG5 in Ngb also take an important role in serving for structural stability and controlling the thermodynamics and kinetics of coordination equilibrium of met-neuroglobin with exterior ligand.