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Bacillus subtilis Fnr senses oxygen via a [4Fe‐4S] cluster coordinated by three cysteine residues without change in the oligomeric state
The oxygen regulator Fnr is part of the regulatory cascade in Bacillus subtilis for the adaptation to anaerobic growth conditions and abolished its in vivo and in vitro activities indicating its importance for intramolecular signal transduction.
PRIMARY CHARGE SEPARATION AND ENERGY TRANSFER IN THE PHOTOSYSTEM I REACTION CENTER OF HIGHER PLANTS
Using low intensity femtosecond duration laser pulses at 708 nm, we have observed absorption transients associated with electron transfer through the primary electron acceptor A0 in the photosystem I…
Kinetic analysis of the thermal stability of the photosynthetic reaction center from Rhodobacter sphaeroides.
The temperature-induced denaturation of the photosynthetic reaction center from Rhodobacter sphaeroides has been studied through the changes that occur in the absorption spectrum of the bound…
Identification and Characterization of a Novel Vitamin B12 (Cobalamin) Biosynthetic Enzyme (CobZ) from Rhodobacter capsulatus, Containing Flavin, Heme, and Fe-S Cofactors*
Recombinant overproduction of Orf663, now renamed CobZ, allowed the characterization of a novel cofactor-rich protein, housing two Fe-S centers, a flavin, and a heme group, which like B12 itself is a modified tetrapyrrole.
Bidirectional electron transfer in photosystem I: electron transfer on the PsaA side is not essential for phototrophic growth in Chlamydomonas.
The Substrate Radical of Escherichia coli Oxygen-independent Coproporphyrinogen III Oxidase HemN*
Observations of an organic radical EPR signal in reduced HemN upon addition of S-adenosyl-l-methionine and the substrate coproporphyrinogen III indicated that, upon abstraction of the pro-S-hydrogen atom at the β-position of the propionate side chain by the 5′-deoxy adenosyl radical, a comparatively stable delocalized substrate radical intermediate is formed in the absence of electron acceptors.
A role for Salmonella typhimurium cbiK in cobalamin (vitamin B12) and siroheme biosynthesis
Results suggest that CbiK can function in fashion analogous to that of the N-terminal domain of CysG (CysG(B)), which catalyzes the final two steps in siroheme synthesis, i.e., NAD-dependent dehydrogenation of precorrin-2 to sirohydrochlorin and ferrochelation.
On the Mechanism of Quinol Oxidation in thebc 1 Complex*
The results indicate that, under conditions of oxidant-induced reduction, the Qo site is occupied primarily by quinol with the iron-sulfur center oxidized, or, possibly, by an antiferromagnetically coupled semiquinone/reduced iron-Sulfurcenter pair, which are EPR silent.
Modelling of the electron transfer reactions in Photosystem I by electron tunnelling theory: the phylloquinones bound to the PsaA and the PsaB reaction centre subunits of PS I are almost isoenergetic…
ATP-driven Reduction by Dark-operative Protochlorophyllide Oxidoreductase from Chlorobium tepidum Mechanistically Resembles Nitrogenase Catalysis*
The heterologous overproduction of DPOR subunits BchN, BchB, and BchL from Chlorobium tepidum in Escherichia coli allowing their purification to apparent homogeneity is described and an enzymatic mechanism ofDPOR is proposed.