Long-range electron transfer across Peptide bridges: the transition from electron superexchange to hopping.
Long-range electron transfer rate constants for complexes of the type [(bpy)2RuIIL-Pron-apyRuIII)(NH3)5]5++ proline residues (n) varying from 0 to 9 were determined by complementary electron pulse radiolysis and flash photolysis techniques from the picosecond to the millisecond time scales. The activationless kmax values from both techniques coalesce into one data set. The distance dependence of the reactions is consistent with a smooth transition from a superexchange mechanism with attenuation constant beta = 1.4 A-1 to a hopping mechanism with attenuation constant beta = 0.17 A-1. The transition occurs between n = 3 and 4 prolines, and the virtual hopping rate constant at the shortest distance is about 1 x 106 times slower than that observed for the superexchange value.
Malak
Rouba Abdel
RA
Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, USA.
Gao
Zhinong
Z
Wishart
James F
JF
Isied
Stephan S
SS
D015082:2,2'-Dipyridyl / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism; D004583:Electrons; D007700:Kinetics; D008667:Metalloproteins / Q000737:chemistry* / Q000378:metabolism; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism; D011392:Proline / Q000031:analogs & derivatives* / Q000378:metabolism; D011675:Pulse Radiolysis; D012428:Ruthenium / Q000737:chemistry* / Q000378:metabolism
D008667:Metalloproteins; D010455:Peptides; D015082:2,2'-Dipyridyl; D012428:Ruthenium; D011392:Proline