By a News Reporter-Staff News Editor at Life Science Weekly -- New research on Proteins is the subject of a report. According to news reporting from Krakow, Poland, by NewsRx journalists, research stated, "Efficient energy conversion often requires stabilization of one-electron intermediates within catalytic sites of redox enzymes. While quinol oxidoreductases are known to stabilize semiquinones, one of the famous exceptions includes the quinol oxidation site of cytochrome bc(1) (Q(o)), for which detection of any intermediate states is extremely difficult."
The news correspondents obtained a quote from the research from Jagiellonian University, "Here we discover a semiquinone at the Q(o) site (SQ(o)) that is coupled to the reduced Rieske cluster (FeS) via spin spin exchange interaction. This interaction creates a new electron paramagnetic resonance (EPR) transitions with the most prominent g = 1.94 signal shifting to 1.96 with an increase in the EPR frequency from X- to Q-band. The estimated value of isotropic spin spin exchange interaction vertical bar J(0)vertical bar = 3500 MHz) indicates that at a lower magnetic field (typical of X-band) the SQ(o)-FeS coupled centers can be described as a triplet state. Concomitantly with the appearance of the SQ(o)- FeS triplet state, we detected a g = 2.0045 radical signal that corresponded to the population of unusually fast-relaxing SQ(o) for which spin spin exchange does not exist or is too small to be resolved. The g = 1.94 and g = 2.0045 signals reached up to 20% of cytochrome bc(1) monomers under aerobic conditions, challenging the paradigm of the high reactivity of SQ(o) toward molecular oxygen. Recognition of stable SQ(o) reflected in g = 1.94 and g = 2.0045 signals offers a new perspective on understanding the mechanism of Q(o) site catalysis."
According to the news reporters, the research concluded: "The frequency-dependent EPR transitions of the SQ(o)-FeS coupled system establish a new spectroscopic approach for the detection of SQ(o) in mitochondria and other bioenergetic systems."
For more information on this research see: Triplet State of the Semiquinone-Rieske Cluster as an Intermediate of Electronic Bifurcation Catalyzed by Cytochrome bc(1). Biochemistry, 2013;52(37):6388-6395. Biochemistry can be contacted at: Amer Chemical Soc, 1155 16TH St, NW, Washington, DC 20036, USA. (American Chemical Society - www.acs.org; Biochemistry - www.pubs.acs.org/journal/bichaw)
Our news journalists report that additional information may be obtained by contacting M. Sarewicz, Jagiellonian University, Dept. of Mol Biophys, Fac Biochem Biophys & Biotechnol, Krakow, Poland. Additional authors for this research include M. Dutka, S. Pintscher and A. Osyczka (see also Proteins).
Keywords for this news article include: Krakow, Poland, Europe, Cytochromes, Hemeproteins, Electron Paramagnetic Resonance
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