Oxygenated and peroxy states of the cytochrome d complex of Escherichia coli have been proposed as intermediates in the reaction mechanism of this ubiquinol oxidase. In this report, several stable states of the purified enzyme were examined spectroscopically at room temperature. As purified, the cytochrome d complex exists in an oxygenated state characterized by an absorbance band at 650 nm. Re...

Fusarium oxysporum JCM11502 expresses a denitrifying (nitrate (NO(3)(-))-respiring) mechanism and can thrive under oxygen (O(2)) limitation. The fungus reduces NO(3)(-) to nitrite at the initial step of denitrification. In this study, we cloned the gene coding NADH-NO(3)(-) reductase (NADH-Nar) (niaD) from F. oxysporum JCM11502. The niaD gene complemented the defective NO(3)(-) assimilation by ...

Coenzyme Q10 (Q10) is present in the circulation mainly in its reduced form (ubiquinol-10; UL10), but oxidizes quickly ex vivo to ubiquinone-10 (UN10). Therefore, native UL10:UN10 ratios, used as markers of redox status and disease risk, are difficult to measure. We established an RP-(U)HPLC method with coulometric detection to measure natively circulating UL10 and UN10 concentrations by adding...

An assay has been developed in which the activity of an ubiquinol oxidase from Escherichia coli, cytochrome bo(3) (cbo(3)), is determined as a function of the hydrophobic substrate ubiquinol-10 (UQ-10) in tethered bilayer lipid membranes (tBLMs). UQ-10 was added in situ, while the enzyme activity and the UQ-10 concentration in the membrane have been determined by cyclic voltammetry. Cbo(3) is i...

To assess the role of cytochrome c2 as a respiratory electron carrier, we obtained a double mutant of Rhodobacter capsulatus defective in cytochrome c2 and in the quinol oxidase260. This mutant was able to grow chemoheterotrophically, indicating that an electron pathway independent of cytochrome c2 was functional between the ubiquinol:cytochrome c2 oxidoreductase and the cytochrome oxidase410.

The respiratory chain cytochrome bc1 complex (cyt bc1) is a major target of numerous antibiotics and fungicides. All cyt bc1 inhibitors act on either the ubiquinol oxidation (QP) or ubiquinone reduction (QN) site. The primary cause of resistance to bc1 inhibitors is target site mutations, creating a need for novel agents that act on alternative sites within the cyt bc1 to overcome resistance. P...

Ubiquinol-cytochrome-c reductase core protein 2 (UQCRC2) is a component of ubiquinol-cytochrome c reductase complex that is known to correlate with male fertility via spermatogenesis. Simultaneously, nutlin-3a is a small molecule antagonist of mouse double minute 2 repressor (MDM2), activate p53 and induce apoptosis responsible for spermatogenesis. To date, however there are no known effects of...

Peripheral arterial disease (PAD) is associated with muscle metabolic changes that may contribute to the disability in these patients. However, the biochemical defects in PAD have not been identified. The present study was undertaken to test the hypothesis that PAD is associated with specific defects in skeletal muscle electron transport chain activity. Seventeen patients with PAD and nine age-...

Decoquinate has single-digit nanomolar activity against in vitro blood stage Plasmodium falciparum parasites, the causative agent of human malaria. In vitro evolution of decoquinate-resistant parasites and subsequent comparative genomic analysis to the drug-sensitive parental strain revealed resistance was conferred by two nonsynonymous single nucleotide polymorphisms in the gene encoding cytoc...