Mesoporous ZnFe O Photoanodes with Template-Tailored Mesopores and Temperature-Dependent Photocurrents.

Mesoporous ZnFe O photoanodes have been prepared via dip-coating utilizing the evaporation-induced self-assembly of two different block-copolymer templates to investigate the influence of pore geometry on the photoelectrochemcial performance of those earth-abundant photoelectrodes. The use of commercial block copolymers, triblock copolymer Pluronic F127 and the diblock copolymer PIB3000 as templates, leads to different pore morphologies under identical preparation conditions due to different polymer stabilities. Interestingly, pore morphology in mesoporous ZnFe O turned out to be less important for the photoelectrochemical performance.

A simulation-guided fluorescence correlation spectroscopy tool to investigate the protonation dynamics of cytochrome c oxidase.

Fluorescence correlation spectroscopy (FCS) is a single molecule based technique to temporally resolve rate-dependent processes by correlating the fluorescence fluctuations of individual molecules traversing through a confocal volume. In addition, chemical processes like protonation or intersystem crossing can be monitored in the sub-microsecond range. FCS thereby provides an excellent tool for investigations of protonation dynamics in proton pumps like cytochrome c oxidase (CcO).

Exploring the entrance of proton pathways in cytochrome c oxidase from Paracoccus denitrificans: surface charge, buffer capacity and redox-dependent polarity changes at the internal surface.

Cytochrome c oxidase (CcO), the terminal oxidase of cellular respiration, reduces molecular oxygen to water. The mechanism of proton pumping as well as the coupling of proton and electron transfer is still not understood in this redox-linked proton pump. Eleven residues at the aqueous-exposed surfaces of CcO from Paracoccus denitrificans have been exchanged to cysteines in a two-subunit base variant to yield single reactive cysteine variants.

Net proton uptake is preceded by multiple proton transfer steps upon electron injection into cytochrome c oxidase.

Cytochrome c oxidase (COX), the last enzyme of the respiratory chain of aerobic organisms, catalyzes the reduction of molecular oxygen to water. It is a redox-linked proton pump, whose mechanism of proton pumping has been controversially discussed, and the coupling of proton and electron transfer is still not understood. Here, we investigated the kinetics of proton transfer reactions following the injection of a single electron into the fully oxidized enzyme and its transfer to the hemes using time-resolved absorption spectroscopy and pH indicator dyes.