Steric Effects in Redox Reactions and Electron Transfer Rates

1997 ◽  
pp. 137-150 ◽  
Author(s):  
Rodney J. Geue ◽  
John V. Hanna ◽  
Arthur Höhn ◽  
C. Jin Qin ◽  
Stephen F. Ralph ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Redox Reactions ◽  
Steric Effects ◽  
Transfer Rates

scholarly journals Metastable radical state, nonreactive with oxygen, is inherent to catalysis by respiratory and photosynthetic cytochromes bc1/b6f

2017 ◽  
Vol 114 (6) ◽  
pp. 1323-1328 ◽  
Author(s):  
Marcin Sarewicz ◽  
Łukasz Bujnowicz ◽  
Satarupa Bhaduri ◽  
Sandeep K. Singh ◽  
William A. Cramer ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Redox Reactions ◽  
Energy Landscape ◽  
Oxygen Species ◽  
Respiratory Enzymes ◽  
Transfer Rates ◽  
Electron Transfer Pathway ◽  
Metal Cofactor ◽  
Radical State ◽  
Oxygen Tensions

Oxygenic respiration and photosynthesis based on quinone redox reactions face a danger of wasteful energy dissipation by diversion of the productive electron transfer pathway through the generation of reactive oxygen species (ROS). Nevertheless, the widespread quinone oxido-reductases from the cytochrome bc family limit the amounts of released ROS to a low, perhaps just signaling, level through an as-yet-unknown mechanism. Here, we propose that a metastable radical state, nonreactive with oxygen, safely holds electrons at a local energetic minimum during the oxidation of plastohydroquinone catalyzed by the chloroplast cytochrome b6f. This intermediate state is formed by interaction of a radical with a metal cofactor of a catalytic site. Modulation of its energy level on the energy landscape in photosynthetic vs. respiratory enzymes provides a possible mechanism to adjust electron transfer rates for efficient catalysis under different oxygen tensions.

Quantification of Electron Transfer Rates to a Solid Phase Electron Acceptor through the Stages of Biofilm Formation from Single Cells to Multicellular Communities

2010 ◽  
Vol 44 (7) ◽  
pp. 2721-2727 ◽  
Author(s):  
Jeffrey S. McLean ◽  
Greg Wanger ◽  
Yuri A. Gorby ◽  
Martin Wainstein ◽  
Jeff McQuaid ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Electron Acceptor ◽  
Biofilm Formation ◽  
Solid Phase ◽  
Single Cells ◽  
Transfer Rates

scholarly journals Electron Transfer Initiated Reactions Photoinduced by Pterins

Pteridines ◽  
2011 ◽  
Vol 22 (1) ◽  
pp. 111-119 ◽  
Author(s):  
Carolina Lorente ◽  
Gabriela Petroselli ◽  
M. Laura Dántola ◽  
Esther Oliveros ◽  
Andrés H. Thomas
Keyword(s):  
Electron Transfer ◽  
Excited State ◽  
Redox Reactions ◽  
Type I ◽  
Biological Processes ◽  
Type Ii ◽  
Triplet Excited State ◽  
Oxygen Production ◽  
Production Type ◽  
Transfer Mechanisms

Abstract Interest in the photochemistry and photophysics of pterins has increased since the participation of this family of compounds in different photobiological processes has been suggested or demonstrated in recent decades. Pterins participate in relevant biological processes, such as metabolic redox reactions, and can photoinduce the oxidation of biomolecules through both electron transfer mechanisms (Type I) and singlet oxygen production (Type II). This article describes recent findings on electron transfer-initiated reactions photoinduced by the triplet excited state of pterins and connects them in the context of photosensitized processes of biological relevance.

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