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PQQ AND Ubiquinol

Aya Ouchi, Kazuto Ikemoto, Masahiko Nakano, Shin-Ichi Nagaoka, Kazuo Mukai
Measurements of aroxyl radical (ArO•)-scavenging rate constants (ks AOH) of antioxidants (AOHs: pyrroloquinolinequinol (PQQH2), α-tocopherol (α-TocH), ubiquinol-10 (UQ10H2), epicatechin, epigallocatechin, epigallocatechin gallate, and caffeic acid) were performed in dimethyl sulfoxide (DMSO) solution, using stopped-flow spectrophotometry. The ks AOH values were measured not only for each AOH but also for the mixtures of two AOHs ((i) α-TocH and PQQH2 and (ii) α-TocH and UQ10H2). A notable synergistic effect that the ks AOH values increase 1...
November 20, 2013: Journal of Agricultural and Food Chemistry
Yan Li, Chang Fu Tian, Wen Feng Chen, Lei Wang, Xin Hua Sui, Wen Xin Chen
The rhizobium-legume symbiosis is a model system for studying mutualistic interactions between bacteria and eukaryotes. Sinorhizobium sp. NGR234 is distinguished by its ability to form either indeterminate nodules or determinate nodules with diverse legumes. Here, we presented a high-resolution RNA-seq transcriptomic analysis of NGR234 bacteroids in indeterminate nodules of Leucaena leucocephala and determinate nodules of Vigna unguiculata. In contrast to exponentially growing free-living bacteria, non-growing bacteroids from both legumes recruited several common cellular functions such as cbb3 oxidase, thiamine biosynthesis, nitrate reduction pathway (NO-producing), succinate metabolism, PHB (poly-3-hydroxybutyrate) biosynthesis and phosphate/phosphonate transporters...
2013: PloS One
Kazuo Mukai, Aya Ouchi, Masahiko Nakano
A kinetic study of the quenching reaction of singlet oxygen ((1)O(2)) with pyrroloquinolinequinol (PQQH(2), a reduced form of pyrroloquinolinequinone (PQQ)), PQQNa(2) (disodium salt of PQQ), and seven kinds of natural antioxidants (vitamin C (Vit C), uric acid (UA), epicatechin (EC), epigallocatechin (EGC), α-tocopherol (α-Toc), ubiquinol-10 (UQ(10)H(2)), and β-carotene (β-Car)) has been performed. The second-order rate constants k(Q) (k(Q) = k(q) + k(r), physical quenching and chemical reaction) for the reaction of (1)O(2) with PQQH(2), PQQNa(2), and seven kinds of antioxidants were measured in 5...
March 9, 2011: Journal of Agricultural and Food Chemistry
Toshiharu Yakushi, Kazunobu Matsushita
Pyrroquinoline quinone-dependent alcohol dehydrogenase (PQQ-ADH) of acetic acid bacteria is a membrane-bound enzyme involved in the acetic acid fermentation by oxidizing ethanol to acetaldehyde coupling with reduction of membranous ubiquinone (Q), which is, in turn, re-oxidized by ubiquinol oxidase, reducing oxygen to water. PQQ-ADHs seem to have co-evolved with the organisms fitting to their own habitats. The enzyme consists of three subunits and has a pyrroloquinoline quinone, 4 heme c moieties, and a tightly bound Q as the electron transfer mediators...
May 2010: Applied Microbiology and Biotechnology
Golam Mustafa, Yoshinori Ishikawa, Kazuo Kobayashi, Catharina T Migita, Seiichi Tagawa, Mamoru Yamada
Membrane-bound glucose dehydrogenase (mGDH) is a single integral protein in the respiratory chain in Escherichia coli which oxidizes D-glucose and feeds electrons to ubiquinol oxidase via bulk ubiquinone (UQ). mGDH contains a bound UQ, CoQ8, for its intramolecular electron transfer in addition to pyrroloquinoline quinone (PQQ) as a coenzyme. Pulse radiolysis analysis revealed that the bound UQ exists very close to PQQ at a distance of 11-13 angstroms. Studies on mGDH mutants with substitutions for amino acid residues around PQQ showed that Asp-466 and Lys-493, which are crucial for catalytic activity, interact with bound UQ...
2008: BioFactors
Kazunobu Matsushita, Yoshiki Kobayashi, Mitsuhiro Mizuguchi, Hirohide Toyama, Osao Adachi, Kimitoshi Sakamoto, Hideto Miyoshi
Quinoprotein alcohol dehydrogenase (ADH) of acetic acid bacteria is a membrane-bound enzyme that functions as the primary dehydrogenase in the ethanol oxidase respiratory chain. It consists of three subunits and has a pyrroloquinoline quinone (PQQ) in the active site and four heme c moieties as electron transfer mediators. Of these, three heme c sites and a further site have been found to be involved in ubiquinone (Q) reduction and ubiquinol (QH2) oxidation respectively (Matsushita et al., Biochim. Biophys...
October 2008: Bioscience, Biotechnology, and Biochemistry
Xue-Peng Yang, Liu-Jing Wei, Jian-Bin Ye, Bo Yin, Dong-Zhi Wei
A membrane-bound pyrroloquinoline quinine (PQQ)-dependent D-sorbitol dehydrogenase (mSLDH) in Gluconobacter oxydans participates in the oxidation of D-sorbitol to L-sorbose by transferring electrons to ubiquinone which links to the respiratory chain. To elucidate the kinetic mechanism, the enzyme purified was subjected to two-substrate steady-state kinetic analysis, product and substrate inhibition studies. These kinetic data indicate that the catalytic reaction follows an ordered Bi Bi mechanism, where the substrates bind to the enzyme in a defined order (first ubiquinone followed by D-sorbitol), while products are released in sequence (first L-sorbose followed by ubiquinol)...
September 15, 2008: Archives of Biochemistry and Biophysics
P M Goodwin, C Anthony
Pyrrolo-quinoline quinone (PQQ) is the non-covalently bound prosthetic group of many quinoproteins catalysing reactions in the periplasm of Gram-negative bacteria. Most of these involve the oxidation of alcohols or aldose sugars. PQQ is formed by fusion of glutamate and tyrosine, but details of the biosynthetic pathway are not known; a polypeptide precursor in the cytoplasm is probably involved, the completed PQQ being transported into the periplasm. In addition to the soluble methanol dehydrogenase of methylotrophs, there are three classes of alcohol dehydrogenases; type I is similar to methanol dehydrogenase; type II is a soluble quinohaemoprotein, having a C-terminal extension containing haem C; type III is similar but it has two additional subunits (one of which is a multihaem cytochrome c), bound in an unusual way to the periplasmic membrane...
1998: Advances in Microbial Physiology
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