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Redox Components (redox + component)

Distribution by Scientific Domains
Life Sciences50%

Selected Abstracts

Radii of Redox Components from Absolute Redox Potentials Compared with Covalent and Aqueous Ionic Radii

ELECTROANALYSIS, Issue 9 2010
Raji Heyrovska
Abstract Aqueous standard potentials, referred to that of the SHE as zero, were recently shown to vary linearly with gaseous ionization potentials, with the absolute potential of SHE as the intercept. This enabled arriving at the absolute redox potentials of elements. Here, the distances between the oxidized and reduced forms in aqueous solutions have been evaluated. From the linear dependence of these distances on the covalent radii of atoms, the radii of the redox components have been obtained. The latter also vary linearly with the aqueous ionic radii estimated earlier from ion-water distances, and indicate the presence of aqueous molecular anions. [source]

Control of chloroplast redox by the IMMUTANS terminal oxidase

PHYSIOLOGIA PLANTARUM, Issue 1 2004
Maneesha R. Aluru
Variegation mutants offer excellent opportunities to study interactions between the nucleus-cytoplasm, the chloroplast, and the mitochondrion. Variegation in the immutans (im) mutant of Arabidopsis is induced by a nuclear recessive gene and the extent of variegation can be modulated by light and temperature. Whereas the green sectors have morphologically normal chloroplasts, the white sectors are devoid of pigments and accumulate a colourless carotenoid, phytoene. The green sectors are hypothesized to arise from cells that have avoided irreversible photooxidative damage whereas the white sectors originate from cells that are photooxidized. Cloning of the IMMUTANS (IM) gene has revealed that IMMUTANS (IM) is a plastid homologue of the mitochondrial alternative oxidase. This finding suggested a model in which IM functions as a redox component of the phytoene desaturation pathway, which requires phytoene desaturase activity. Consistent with this idea, IM has quinol oxidase activity in vitro. Recent studies have revealed that IM plays a more global role in plastid metabolism. For example, it appears to be the elusive terminal oxidase of chlororespiration and also functions as a light stress protein. [source]

Radii of Redox Components from Absolute Redox Potentials Compared with Covalent and Aqueous Ionic Radii

ELECTROANALYSIS, Issue 9 2010
Raji Heyrovska
Abstract Aqueous standard potentials, referred to that of the SHE as zero, were recently shown to vary linearly with gaseous ionization potentials, with the absolute potential of SHE as the intercept. This enabled arriving at the absolute redox potentials of elements. Here, the distances between the oxidized and reduced forms in aqueous solutions have been evaluated. From the linear dependence of these distances on the covalent radii of atoms, the radii of the redox components have been obtained. The latter also vary linearly with the aqueous ionic radii estimated earlier from ion-water distances, and indicate the presence of aqueous molecular anions. [source]

Compensatory thio,redox interactions between DsbA, CcdA and CcmG unveil the apocytochrome c holdase role of CcmG during cytochrome c maturation

MOLECULAR MICROBIOLOGY, Issue 3 2008
Serdar Turkarslan
Summary During cytochrome c maturation (Ccm), the DsbA-dependent thio-oxidative protein-folding pathway is thought to introduce a disulphide bond into the haem-binding motif of apocytochromes c. This disulphide bond is believed to be reduced through a thio-reductive pathway involving the Ccm components CcdA (DsbD), CcmG and CcmH. Here, we show in Rhodobacter capsulatus that in the absence of DsbA cytochrome c levels were decreased and CcdA or CcmG or the putative glutathione transporter CydDC was not needed for Ccm. This decrease was not due to overproduction of the periplasmic protease DegP as a secondary effect of DsbA absence. In contrast, CcmH was absolutely necessary regardless of DsbA, indicating that compensatory thio,redox interactions excluded it. Remarkably, the double (DsbA,CcmG) and triple (DsbA,CcmG,CcdA) mutants produced cytochromes c at lower levels than the DsbA-null mutants, unless they contained a CcmG derivative (CcmG*) lacking its thio-reductive activity. Purified CcmG* can bind apocytochrome c in vitro, revealing for the first time a thiol-independent, direct interaction between apocytochrome c and CcmG. Furthermore, elimination of the thio,redox components does not abolish cytochrome c production, restricting the number of Ccm components essential for haem,apocyt c ligation per se during Ccm. [source]