Proton transfer is critical in many important biochemical reactions. The unique three-step excited-state proton transfer in avGFP allows observations of protein proton transport in real-time. In this work we exploit femtosecond to microsecond transient IR spectroscopy to record, in D2 O, the complete proton transfer photocycle of avGFP, and two mutants (T203V and S205V) which modify the structu...

In cytochrome c oxidase, a requirement for proton pumping is a tight coupling between electron and proton transfer, which could be accomplished if internal electron-transfer rates were controlled by uptake of protons. During reaction of the fully reduced enzyme with oxygen, concomitant with the "peroxy" to "oxoferryl" transition, internal transfer of the fourth electron from CuA to heme a has t...

The reaction mechanisms by which antioxidants can exert their activity are: hydrogen atom transfer (HAT), proton coupled electron transfer (PCET), sequential proton loss electron transfer (SPLET), single electron transfer proton transfer (SET-PT), radical adduct formation, and sequential proton loss hydrogen atom transfer. The antioxidative activity of different compounds (flavones, flavonols, ...

In the photosynthetic reaction center (RC) from Rhodobacter sphaeroides, the reduction of a bound quinone molecule Q(B) is coupled with proton uptake. When Asp-L213 is replaced by Asn, proton transfer is inhibited. Proton transfer was restored by two second-site revertant mutations, Arg-M233-->Cys and Arg-H177-->His. Kinetic effects of Cd(2+) on proton transfer showed that the entry point in re...

In the light-driven bacteriorhodopsin proton pump, the first proton transfer step is from the retinal Schiff base to a nearby carboxylate group. The mechanism of this transfer step is highly controversial, in particular whether a direct proton jump is allowed. Here, we review the structural and energetic determinants of the direct proton transfer path computed by using a combined quantum mechan...

Proton transfer rates and mechanisms are studied in mesoscopic, liquid-state, molecular clusters. The proton transfer occurs in a protonion complex solvated by polar molecules comprising the cluster environment. The rates and mechanisms of the reaction are studied using both adiabatic and non-adiabatic molecular dynamics. For large molecular clusters, the proton-ion complex resides primarily on...

Membrane protein complexes can support both the generation and utilisation of a transmembrane electrochemical proton potential ('proton-motive force'), either by transmembrane electron transfer coupled to protolytic reactions on opposite sides of the membrane or by transmembrane proton transfer. Here we provide the first evidence that both of these mechanisms are combined in the case of a speci...

Bacteriorhodopsin is a proton-pumping membrane protein found in the plasma membrane of the archaeon Halobacterium salinarium. Light-induced isomerization of the retinal chromophore from all-trans to 13-cis leads to a sequence of five conformation-coupled proton transfer steps and the net transport of one proton from the cytoplasmic to the extracellular side of the membrane. The mechanism of the...

Proton transfer reactions play an important role in many areas of biology. We reimplemented a method introduced by Taraphder et al. to characterize putative proton transfer pathways in proteins along hydrogen bonded networks and could retrace their results on cytochrome P450cam. By combining this method with our established Q-HOP approach to compute proton transfer probabilities we present here...

Articles you may be interested in Quantum and dynamical effects of proton donor-acceptor vibrational motion in nonadiabatic proton-coupled electron transfer reactions Predictions of rate constants and estimates for tunneling splittings of concerted proton transfer in small cyclic water clusters Tunneling currents in long-distance electron transfer reactions. IV. Many-electron formulation. Nonor...