Preparation, characterization, and intramolecular electron transfer in pentaammineruthenium histidine-26 cytochrome b5 derivatives: role of the intervening medium in long-range donor-acceptor electronic coupling

1991 ◽  
Vol 113 (12) ◽  
pp. 4390-4394 ◽  
Author(s):  
Bradley A. Jacobs ◽  
Marcia R. Mauk ◽  
Walter D. Funk ◽  
Ross T. A. MacGillivray ◽  
A. Grant Mauk ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Long Range ◽  
Cytochrome B5 ◽  
Electronic Coupling ◽  
Intramolecular Electron Transfer ◽  
Donor Acceptor

scholarly journals Fluctuating hydrogen-bond networks govern anomalous electron transfer kinetics in a blue copper protein

2018 ◽  
Vol 115 (24) ◽  
pp. 6129-6134 ◽  
Author(s):  
Joshua S. Kretchmer ◽  
Nicholas Boekelheide ◽  
Jeffrey J. Warren ◽  
Jay R. Winkler ◽  
Harry B. Gray ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Electron Transfer ◽  
Hydrogen Bonds ◽  
Long Range ◽  
Driving Forces ◽  
Reorganization Energy ◽  
Electronic Coupling ◽  
Hydrogen Bond Networks ◽  
Donor Acceptor ◽  
Network Of Hydrogen Bonds

We combine experimental and computational methods to address the anomalous kinetics of long-range electron transfer (ET) in mutants of Pseudomonas aeruginosa azurin. ET rates and driving forces for wild type (WT) and three N47X mutants (X = L, S, and D) of Ru(2,2′-bipyridine)2 (imidazole)(His83) azurin are reported. An enhanced ET rate for the N47L mutant suggests either an increase of the donor–acceptor (DA) electronic coupling or a decrease in the reorganization energy for the reaction. The underlying atomistic features are investigated using a recently developed nonadiabatic molecular dynamics method to simulate ET in each of the azurin mutants, revealing unexpected aspects of DA electronic coupling. In particular, WT azurin and all studied mutants exhibit more DA compression during ET (>2 Å) than previously recognized. Moreover, it is found that DA compression involves an extended network of hydrogen bonds, the fluctuations of which gate the ET reaction, such that DA compression is facilitated by transiently rupturing hydrogen bonds. It is found that the N47L mutant intrinsically disrupts this hydrogen-bond network, enabling particularly facile DA compression. This work, which reveals the surprisingly fluctional nature of ET in azurin, suggests that hydrogen-bond networks can modulate the efficiency of long-range biological ET.

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