The road also taken: Alternative and hidden pathways in biological electron transfer
(Phys.org)—Photosynthesis, cellular respiration and many other biological processes have something in common: long-range electron transfer (ET), the simplest known chemical reaction that is known to occur efficiently high over distances up to 20 Å. However, determining the ways in which biological electron transfer is optimized has been a subject of considerable discussion. Recently, scientists at Universidad Nacional de Rosario and Universidad de Buenos Aires, Argentina conducted a spectroscopic, electrochemical, and theoretical study that suggests a unique role for alternative or "invisible" electronic ground states corresponding to directional electron transfer. Specifically, they describe a biological redox metal center (CuA) in which thermal fluctuations in Thermus thermophilus may populate two alternative ground-state electronic wave functions optimized for electron entry and exit, respectively, through two different and nearly perpendicular pathways.