Carnitine metabolism in the human gut: characterization of the two-component carnitine monooxygenase CntAB from .

Bacterial formation of trimethylamine (TMA) from carnitine in the gut microbiome has been linked to cardiovascular disease. During this process, the two-component carnitine monooxygenase (CntAB) catalyzes the oxygen-dependent cleavage of carnitine to TMA and malic semialdehyde. Individual redox states of the reductase CntB and the catalytic component CntA were investigated based on mutagenesis and electron paramagnetic resonance (EPR) spectroscopic approaches.

Importance of Hydrogen Bonding in Fine Tuning the [2Fe-2S] Cluster Redox Potential of HydC from Thermotoga maritima.

Iron-sulfur clusters form one of the largest and most diverse classes of enzyme cofactors in nature. They may serve as structural factors, form electron transfer chains between active sites and external redox partners, or form components of enzyme active sites. Their specific role is a consequence of the cluster type and the surrounding protein environment.

Möbius-Hückel topology switching in an expanded porphyrin cation radical as studied by EPR and ENDOR spectroscopy.

The symmetry of the arrangement of objects has fascinated philosophers, artists and scientists for a long time, and still does. Symmetries often exist in nature, but are also created artificially, for instance by chemical synthesis of novel molecules and materials. The one-sided, non-orientable Möbius band topology is a paradigm of such a symmetry-based fascination.

A heme-based redox sensor in the methanogenic archaeon Methanosarcina acetivorans.

Based on a bioinformatics study, the protein MA4561 from the methanogenic archaeon Methanosarcina acetivorans was originally predicted to be a multidomain phytochrome-like photosensory kinase possibly binding open-chain tetrapyrroles. Although we were able to show that recombinantly produced and purified protein does not bind any known phytochrome chromophores, UV-visible spectroscopy revealed the presence of a heme tetrapyrrole cofactor. In contrast to many other known cytoplasmic heme-containing proteins, the heme was covalently attached via one vinyl side chain to cysteine 656 in the second GAF domain.

The unusal redox centers of SoxXA, a novel c-type heme-enzyme essential for chemotrophic sulfur-oxidation of Paracoccus pantotrophus.

The heterodimeric hemoprotein SoxXA, essential for lithotrophic sulfur oxidation of the aerobic bacterium Paracoccus pantotrophus, was examined by a combination of spectroelectrochemistry and EPR spectroscopy. The EPR spectra for SoxXA showed contributions from three paramagnetic heme iron centers. One highly anisotropic low-spin (HALS) species (gmax = 3.

Spectroelectrochemical characterization of the [NiFe] hydrogenase of Desulfovibrio vulgaris Miyazaki F.

The active site in the [NiFe] hydrogenase of Desulfovibrio vulgaris Miyazaki F has been investigated by Fourier transform infrared (FTIR) spectroscopy. Analysis of the spectra allowed the three diatomic inorganic ligands to Fe in this enzyme to be identified as one CO molecule and two CN(-) molecules. Furthermore, pH-dependent redox titrations were performed to determine the midpoint potentials as well as the pK value of the respective reactions and revealed that each single-electron redox transition is accompanied by a single-proton transfer step.