Gradinaru Cristian, Crane Brian R
J Phys Chem B. 2006 Oct 19;110(41):20073-6. doi: 10.1021/jp0644309.
Selective metal-ion incorporation and ligand substitution are employed to control whether electrons tunnel over intra- or intermolecular separations in crystals of P. aeruginosa azurin modified with Ru-polypyridine complexes. Cu(1+)-to-Ru3+ electron transfer (ET) across a specific protein-protein interface in the crystal lattice has a time constant 5-10 times longer than ET between the same donor and acceptor within a single protein (tauET = 5 vs 0.5-1.0 micros). Slower intermolecular ET agrees well with a longer distance between redox centers across the inter-protein (18.9 A) compared to the intra-protein separation (17.0 A) and indicates that the closest donor/acceptor pair dominates crystal ET. Lowering the crystal pH accelerates inter-protein ET (tauET = 1.0 micros) but not intra-protein ET. Faster inter-protein ET likely results from a pH-induced peptide bond flip that perturbs hydrogen bonding in the path between Ru and Cu centers on adjacent molecules.
利用选择性金属离子掺入和配体取代来控制电子是通过分子内还是分子间距离在经钌-多吡啶配合物修饰的铜绿假单胞菌天青蛋白晶体中隧穿。晶格中特定蛋白质-蛋白质界面上从Cu(1+)到Ru3+的电子转移（ET）的时间常数比单个蛋白质内相同供体和受体之间的ET长5至10倍（tauET = 5微秒对0.5 - 1.0微秒）。与蛋白质内距离（17.0 Å）相比，跨蛋白质间氧化还原中心之间更长的距离（18.9 Å）使得分子间ET较慢，这表明最接近的供体/受体对主导晶体ET。降低晶体pH会加速蛋白质间ET（tauET = 1.0微秒），但不会加速蛋白质内ET。更快的蛋白质间ET可能是由于pH诱导的肽键翻转扰乱了相邻分子上Ru和Cu中心之间路径中的氢键所致。
