Ubiquinone (coenzyme Q) and the respiratory chain

Comprehensive transcriptomic and proteomic analyses of antroquinonol biosynthetic genes and enzymes in Antrodia camphorata

Antroquinonol (AQ) has several remarkable bioactivities in acute myeloid leukaemia and pancreatic cancer, but difficulties in the mass production of AQ hamper its applications. Currently, molecular biotechnology methods, such as gene overexpression, have been widely used to increase the production of metabolites. However, AQ biosynthetic genes and enzymes are poorly understood. In this study, an integrated study coupling RNA-Seq and isobaric tags for relative and absolute quantitation (iTRAQ) were used to identify AQ synthesis-related genes and enzymes in Antrodia camphorata during coenzyme Q0-induced fermentation (FM). The upregulated genes related to acetyl-CoA synthesis indicated that acetyl-CoA enters the mevalonate pathway to form the farnesyl tail precursor of AQ. The metE gene for an enzyme with methyl transfer activity provided sufficient methyl groups for AQ structure formation. The CoQ2 and ubiA genes encode p-hydroxybenzoate polyprenyl transferase, linking coenzyme Q0 and the polyisoprene side chain to form coenzyme Q3. NADH is transformed into NAD+ and releases two electrons, which may be beneficial for the conversion of coenzyme Q3 to AQ. Understanding the biosynthetic genes and enzymes of AQ is important for improving its production by genetic means in the future.

Mitochondrial Therapies in Heart Failure

The current therapy for patients with stable systolic heart failure is largely limited to treatments that interfere with neurohormonal activation. Critical pathophysiological hallmarks of heart failure are an energetic deficit and oxidative stress, and both may be the result of mitochondrial dysfunction. This dysfunction is not (only) the result of defect within mitochondria per se, but is in particular traced to defects in intermediary metabolism and of the regulatory interplay between excitation-contraction coupling and mitochondrial energetics, where defects of cytosolic calcium and sodium handling in failing hearts may play important roles. In the past years, several therapies targeting mitochondria have emerged with promising results in preclinical models. Here, we discuss the mechanisms and results of these mitochondria-targeted therapies, but also of interventions that were not primarily thought to target mitochondria but may have important impact on mitochondrial biology as well, such as iron and exercise. Future research should be directed at further delineating the details of mitochondrial dysfunction in patients with heart failure to further optimize these treatments.

Chemiosmotic coupling in oxidative and photosynthetic phosphorylation. 1966

50 years ago Peter Mitchell proposed the chemiosmotic hypothesis for which he was awarded the Nobel Prize for Chemistry in 1978. His comprehensive review on chemiosmotic coupling known as the first "Grey Book", has been reprinted here with permission, to offer an electronic record and easy access to this important contribution to the biochemical literature. This remarkable account of Peter Mitchell's ideas originally published in 1966 is a landmark and must-read publication for any scientist in the field of bioenergetics. As far as was possible, the wording and format of the original publication have been retained. Some changes were required for consistency with BBA formats though these do not affect scientific meaning. A scanned version of the original publication is also provided as a downloadable file in Supplementary Information and can be found online at doi:10.1016/j.bbabio.2011.09.018. See also Editorial in this issue by Peter R. Rich. Original title: CHEMIOSMOTIC COUPLING IN OXIDATIVE AND PHOTOSYNTHETIC PHOSPHORYLATION, by Peter Mitchell, Glynn Research Laboratories, Bodmin, Cornwall, England.

6-Vinyl coenzyme Q0: Electropolymerization and electrocatalysis of NADH oxidation exploiting poly-p-quinone-modified electrode surfaces

6-Vinyl coenzyme Q(0) serves as a convenient starting material for the formation of electropolymerized coenzyme Q(0) on glassy carbon electrodes and the modified electrodes displays electrocatalytic activity toward NADH (β-nicotinamide adenine dinucleotide) oxidation. The detection of NADH was measured by differential pulse voltammetry, which reveals that the peak current is linear to the concentration of NADH within the range of 10-100μM. This would be helpful for the understanding of the interaction between coenzyme Q(0) and NADH in the biological process.

Studies on the antibacterial and antifungal properties of 1, 4-naphthoquinones

1. New halogenated 1,4-naphthoquinones were synthesized and together with other known 1,4-naphthoquinones, were screened for antibacterial activity by a turbidimetric method, and for antifungal activity by the diffusion method on agar plates.2. The half-wave potentials and the influence on the oxidative phosphorylation of some of these compounds were determined.3. 2-chloro-3,2'-chloro-ethyl-1,4-naphthoquinone (half-wave potential=-187 mV) was the most active compound, completely inhibiting cell respiration.4. While the natural active naphthoquinones, vitamin K and ubiquinones, possess, as substituent, the electron repelling methyl group, the microbiologically active 1,4-naphthoquinones are substituted, in the quinone moiety, with electron attracting groups such as OH or Cl.5. The half-wave potentials can give only an initial indication of the activity of the compounds studied; a good correlation, on the contrary, can be found between the ultraviolet spectra of such compounds and their activity which seems to depend on the ability of active compounds to exist in an extensively conjugated structure and to form hydrogen bonds.