Electron tunneling in rhenium-modified Pseudomonas aeruginosa azurins.
Laser flash-quench methods have been used to generate tyrosine and tryptophan radicals in structurally characterized rhenium-modified Pseudomonas aeruginosa azurins. Cu(I) to "Re(II)" electron tunneling in Re(H107) azurin occurs in the microsecond range. This reaction is much faster than that studied previously for Cu(I) to Ru(III) tunneling in Ru(H107) azurin, suggesting that a multistep ("hopping") mechanism might be involved. Although a Y108 radical can be generated by flash-quenching a Re(H107)M(II) (M=Cu, Zn) protein, the evidence suggests that it is not an active intermediate in the enhanced Cu(I) oxidation. Rather, the likely explanation is rapid conversion of Re(II)(H107) to deprotonated Re(I)(H107 radical), followed by electron tunneling from Cu(I) to the hole in the imidazole ligand.
Miller
Jeremiah E
JE
Beckman Institute, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA.
Di Bilio
Angel J
AJ
Wehbi
William A
WA
Green
Michael T
MT
Museth
A Katrine
AK
Richards
John R
JR
Winkler
Jay R
JR
Gray
Harry B
HB
D001400:Azurin / Q000737:chemistry* / Q000378:metabolism*; D003300:Copper / Q000737:chemistry; D004579:Electron Transport; D008958:Models, Molecular; D010084:Oxidation-Reduction; D011550:Pseudomonas aeruginosa / Q000378:metabolism; D012211:Rhenium / Q000737:chemistry
D001400:Azurin; D012211:Rhenium; D003300:Copper