Establishing mechanisms and intrinsic reactivity in the oxidation of phenol with water as the proton acceptor is a fundamental task relevant to many reactions occurring in natural systems. Thanks to the easy measure of the reaction kinetics by the current and the setting of the driving force by the electrode potential, the electrochemical approach is particularly suited to this endeavor. Despit...

FTIR spectroscopy is advantageous for detecting changes in polar chemical bonds that participate in bacterio rhodopsin function. Changes in H bonding of Asp85, Asp96, the Schiff base, and internal water molecules around these residues upon the formation of the L, M, and N photo intermediates of bacteriorhodopsin were investigated by difference FTIR spectroscopy. The locations and the interactio...

The reaction center (RC) from Rhodobacter sphaeroides converts light into chemical energy through the light induced two-electron, two-proton reduction of a bound quinone molecule QB (the secondary quinone acceptor). A unique pathway for proton transfer to the QB site had so far not been determined. To study the molecular basis for proton transfer, we investigated the effects of exogenous metal ...

A model Hamiltonian for photoinduced homogeneous proton-coupled electron transfer reactions is presented, and the equations of motion for the reduced density matrix elements in an electron-proton vibronic basis are derived. This formalism enables a detailed analysis of the proton vibrational dynamics, as well as the dynamics of the electronic state populations, following photoexcitation. The ap...

Proton conductors (PCs) are multifunctional perovskite materials with structural, electrical, and chemical compatibilities that serve as principal components in proton conducting solid oxide fuel cells (PC-SOFC). The synergetic advantages of PC-SOFC dominate lucrative applications conventional SOFC. However, adequate accompany certain key limitations PCs. inverse interplay between conductivity ...

Light induced multisite electron proton transfer in two different phenol (simple and phenol carrying an intramolecularly hydrogen bonded base) pendants on acridinedione dye (ADD) and an NADH analogue was studied by following fluorescence quenching dynamics in an ultrafast timescale. In a simple phenol derivative (ADDOH), photo-excited acridinedione acquires an electron from phenol intramolecula...

The ability of COz to stimulate the Hill reaction in thylakoid membrane is well established [ 11. When NaHCOs is added to COz-depleted thylakoids, a large (4-6-fold) increase in oxygen evolution is observed. Recent experiments [2-61 have demonstrated that a major site of inhibition of Hill reaction by CO2 depletion is between electron acceptor Q of photosystem II (PS II) and the plastoquinone (...

Through the use of site-directed mutagenesis and chemical rescue, we have identified the proton acceptor for redox-active tyrosine D in photosystem II (PSII). Effects of chemical rescue on the tyrosyl radical were monitored by EPR spectroscopy. We also have acquired the Fourier-transform infrared (FT-IR) spectrum associated with the oxidation of tyrosine D and concomitant protonation of the acc...

Cytochrome c oxidase is the terminal enzyme of the respiratory chain that is responsible for biological energy conversion in mitochondria and aerobic bacteria. The membrane-bound enzyme converts free energy from oxygen reduction to an electrochemical proton gradient by functioning as a redox-coupled proton pump. Although the 3D structure and functional studies have revealed proton conducting pa...