Ruthenium-modified cytochrome c: temperature dependence of the rate of intramolecular electron transfer

1984 ◽  
Vol 106 (6) ◽  
pp. 1722-1726 ◽  
Author(s):  
Stephan S. Isied ◽  
Christa Kuehn ◽  
Greg Worosila
Keyword(s):  
Electron Transfer ◽  
Cytochrome C ◽  
Temperature Dependence ◽  
Intramolecular Electron Transfer

Role of methionine 230 in intramolecular electron transfer between the oxyferryl heme and tryptophan 191 in cytochrome c peroxidase compound II

Biochemistry ◽  
1994 ◽  
Vol 33 (29) ◽  
pp. 8678-8685 ◽  
Author(s):  
Rui-Qin Liu ◽  
Mark A. Miller ◽  
Gye Won Han ◽  
Seung Hahm ◽  
Lois Geren ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Cytochrome C ◽  
Cytochrome C Peroxidase ◽  
Intramolecular Electron Transfer ◽  
Compound Ii

Routes of electron transfer in beef heart cytochrome c oxidase: is there a unique pathway used by all reductants?

1992 ◽  
Vol 70 (5) ◽  
pp. 301-308 ◽  
Author(s):  
M. Crinson ◽  
P. Nicholls
Keyword(s):  
Electron Transfer ◽  
Steady State ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Reduction Rate ◽  
Artificial Substrates ◽  
Intramolecular Electron Transfer ◽  
State Reduction ◽  
Hydrogen Donors ◽  
Slow Turnover

Cytochrome c oxidase oxidizes several hydrogen donors, including TMPD (N,N,N′,N′-tetramethyl-p-phenylenediamine) and DMPT (2-amino-6,7-dimethyl-5,6,7,8-tetrahydropterine), in the absence of the physiological substrate cytochrome c. Maximal enzyme turnovers with TMPD and DMPT alone are rather less than with cytochrome c, but much greater than previously reported if extrapolated to high reductant levels and (or) to 100% reduction of cytochrome a in the steady state. The presence of cytochrome c is, therefore, not necessary for substantial intramolecular electron transfer to occur in the oxidase. A direct bimolecular reduction of cytochrome a by TMPD is sufficient to account for the turnover of the enzyme. CuA may not be an essential component of the TMPD oxidase pathway. DMPT oxidation seems to occur more rapidly than the DMPT – cytochrome a reduction rate and may therefore imply mediation of CuA. Both "resting" and "pulsed" oxidases contain rapid-turnover and slow-turnover species, as determined by aerobic steady-state reduction of cytochrome a by TMPD. Only the "rapid" fraction (≈70% of the total with resting and ≈85% of the total with pulsed) is involved in turnover. We conclude that electron transfer to the a3CuB binuclear centre can occur either from cytochrome a or CuA, depending upon the redox state of the binuclear centre. Under steady-state conditions, cytochrome a and CuA may not always be in rapid equilibrium. Rapid enzyme turnover by either natural or artificial substrates may require reduction of both and two pathways of electron transfer to the a3CuB centre.Key words: cytochrome c oxidase, cytochrome a, respiration, cyanide, stopped flow.

Superexchange in the fast lane – intramolecular electron transfer in a molecular triad occurs by conformationally gated superexchange

2019 ◽  
Vol 55 (36) ◽  
pp. 5251-5254 ◽  
Author(s):  
Yusen Luo ◽  
Maria Wächtler ◽  
Kevin Barthelmes ◽  
Andreas Winter ◽  
Ulrich S. Schubert ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Temperature Dependence ◽  
Photoinduced Electron Transfer ◽  
Intramolecular Electron Transfer ◽  
Fast Lane

Photoinduced electron transfer via hopping is generally considered to have a stronger temperature dependence than electron transfer via superexchange.

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