PMID- 12668481
OWN - NLM
STAT- MEDLINE
DCOM- 20031209
LR  - 20181113
IS  - 0006-3495 (Print)
IS  - 1542-0086 (Electronic)
IS  - 0006-3495 (Linking)
VI  - 84
IP  - 4
DP  - 2003 Apr
TI  - Kinetics of intramolecular electron transfer in cytochrome bo3 from Escherichia 
      coli.
PG  - 2728-33
AB  - We have examined the temperature dependence of the intramolecular electron 
      transfer (ET) between heme b and heme o(3) in CO-mixed valence cytochrome bo(3) 
      (Cbo) from Escherichia coli. Upon photolysis of CO-mixed valence Cbo rapid ET 
      occurs between heme o(3) and heme b with a rate constant of 2.2 x 10(5) s(-1) at 
      room temperature. The corresponding rate of CO recombination is found to be 86 
      s(-1). From Eyring plots the activation energies for these two processes are 
      found to be 3.4 kcal/mol and 6.7 kcal/mol for the ligand binding and ET 
      reactions, respectively. Using variants of the Marcus equation the reorganization 
      energy (lambda), electronic coupling factor (H(AB)), and the ET distance were 
      found to be 1.4 +/- 0.2 eV, (2 +/- 1) x 10(-3) eV, and 9 +/- 1 A, respectively. 
      These values are quite distinct from the analogous values previously obtained for 
      bovine heart cytochrome c oxidase (CcO) (0.76 eV, 9.9 x 10(-5) eV, 13.2 A). The 
      differences in mechanisms/pathways for heme b/heme o(3) and heme a/heme a(3) ET 
      suggested by the Marcus parameters can be attributed to structural changes at the 
      Cu(B) site upon change in oxidation state as well as differences in electronic 
      coupling pathways between Heme b and heme o(3).
FAU - Ching, Erin
AU  - Ching E
AD  - Department of Chemistry, University of Hawaii, Honolulu, Hawaii 96822, USA.
FAU - Gennis, Robert B
AU  - Gennis RB
FAU - Larsen, Randy W
AU  - Larsen RW
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, Non-P.H.S.
PL  - United States
TA  - Biophys J
JT  - Biophysical journal
JID - 0370626
RN  - 42VZT0U6YR (Heme)
RN  - 789U1901C5 (Copper)
SB  - IM
MH  - Copper/*chemistry
MH  - Electron Transport
MH  - Enzyme Activation
MH  - Escherichia coli/*chemistry/enzymology
MH  - Heme/*chemistry
MH  - Kinetics
MH  - *Models, Molecular
MH  - Spectrum Analysis/*methods
MH  - *Temperature
PMC - PMC1302839
EDAT- 2003/04/02 05:00
MHDA- 2003/12/10 05:00
PMCR- 2004/04/01
CRDT- 2003/04/02 05:00
PHST- 2003/04/02 05:00 [pubmed]
PHST- 2003/12/10 05:00 [medline]
PHST- 2003/04/02 05:00 [entrez]
PHST- 2004/04/01 00:00 [pmc-release]
AID - S0006-3495(03)75078-4 [pii]
AID - 16048 [pii]
AID - 10.1016/S0006-3495(03)75078-4 [doi]
PST - ppublish
SO  - Biophys J. 2003 Apr;84(4):2728-33. doi: 10.1016/S0006-3495(03)75078-4.