Measuring mitochondrial electron transfer complexes in previously frozen cardiac tissue from the offspring of sow: A model to assess exercise induced mitochondrial bioenergetics changes

Measuring the mitochondrial electron transfer complex (ETC) profile from previously frozen heart tissue samples from offspring born to an exercised sow provided descriptive data about exercise induced mitochondrial biochemical changes in heart tissue from the offspring born to the exercised sow. The hypothesis that was proposed and tested was that regular maternal exercise of a sow during pregnancy would increase the mitochondrial efficiency of offspring heart bioenergetics. This hypothesis was tested by isolating mitochondria using a mild-isolation procedure so that mitochondrial ETC, and supercomplex profiles were assessed. The procedure described here allowed for the processing of previously frozen archived heart tissues, and eliminated the necessity of fresh mitochondria preparation for the assessment of mitochondrial ETC complexes, supercomplexes, and ETC complex activity profiles. This protocol described the optimal ETC protein complex measurement in multiplexed antibody-based immunoblotting, and super complex assessment using blue-native gel electrophoresis.

Electron transfer within β-diketiminato nickel bromide and cobaltocene redox couples activating CO2

Even though β-diketiminato nickel(ii) bromide and cobaltocene have nearly identical redox potentials the corresponding electron transfer complex can be crystallised from the equilibrium and activates CO2 to form a mononuclear nickel(ii) carbonate.

Structures of substrate- and product-bound forms of a multi-domain copper nitrite reductase shed light on the role of domain tethering in protein complexes

Copper-containing nitrite reductases (CuNiRs) are found in all three kingdoms of life and play a major role in the denitrification branch of the global nitrogen cycle where nitrate is used in place of dioxygen as an electron acceptor in respiratory energy metabolism. Several C- and N-terminal redox domain tethered CuNiRs have been identified and structurally characterized during the last decade. Our understanding of the role of tethered domains in these new classes of three-domain CuNiRs, where an extra cytochrome or cupredoxin domain is tethered to the catalytic two-domain CuNiRs, has remained limited. This is further compounded by a complete lack of substrate-bound structures for these tethered CuNiRs. There is still no substrate-bound structure for any of the as-isolated wild-type tethered enzymes. Here, structures of nitrite and product-bound states from a nitrite-soaked crystal of the N-terminal cupredoxin-tethered enzyme from the Hyphomicrobium denitrificans strain 1NES1 (Hd 1NES1NiR) are provided. These, together with the as-isolated structure of the same species, provide clear evidence for the role of the N-terminal peptide bearing the conserved His27 in water-mediated anchoring of the substrate at the catalytic T2Cu site. Our data indicate a more complex role of tethering than the intuitive advantage for a partner-protein electron-transfer complex by narrowing the conformational search in such a combined system.

An inorganic molecule-induced electron transfer complex for highly efficient organic solar cells

A series of inorganic polynuclear metaloxo clusters (PMCs) were studied as anode interlayers for fabricating high-performance organic solar cells. And, the mechanism of forming an inorganic–organic electron transfer complex was revealed.

Electron transfer complexes in the gut dictate high abundance circulating metabolites

It has long been thought that Clostridium and its relatives couple the oxidation of one substrate to the reduction of another, yielding energy in the former step and re-achieving redox balance with the latter. By probing the genetics of reductive metabolic pathways in the gut resident C. sporogenes, we find unexpectedly that electron transfer complexes are required for the production of reduced metabolites. Physiologic measurements in vitro indicate that the reductive pathways are coupled to ATP formation, revealing that energy is captured not just during substrate oxidation, but also during coupled reduction, accounting for ~40% of the ATP generated in the cell. Electron transfer complex mutants are attenuated for growth in the mouse gut, demonstrating the importance of energy capture during reductive metabolism for gut colonization. Our findings revise a long-standing model for energy capture by Clostridium sp., and they reveal that the production of high-abundance molecules by a commensal bacterium within the host gut is linked to an energy yielding redox process.