Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.12.7.2 (hydrogenase)
 3,522 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Measurements with a PAM fluorometer showed that the photochemical activity of photosystem II (PS II) in sulfur-deprived Chlamydomonas reinhardtii cells (media TAP-S) decreases slowly under aerobic conditions. In a closed cultivator, when the rate of O2 photosynthetic evolution declines below the rate of respiration, the cell culture is under anaerobic conditions in which the activation of hydrogenase and the production of hydrogen take place. We found that the slow decrease in PS II activity is followed by an abrupt inactivation of PS II centers just after the onset of anaerobiosis. This fast PS II inactivation is reversed by aeration of the media and is accompanied by an increase in the fluorescence parameter Ft. Moreover, the rate of the abrupt PS II inactivation diminished after the addition into the medium of electron acceptors such as CO2 (carbonate-bicarbonate buffer), NO3- and SO4(2-) , the assimilation of which in chloroplasts requires a lot of reductants. We suggest that the PS II inactivation is due to the overreduction of the plastoquinone pool after the onset of anaerobiosis.
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PMID:[The photochemical activity of photosystem II in sulfur-deprived Chlamydomonas reinhardtii cells depends on the redox state of the quinone pool during the transition to anaerobiosis]. 1532 9

Oxidative stress conditions lead to enzymatic and non-enzymatic unsaturated fatty acid-initiated lipid peroxidation reactions. One exacerbating product is lipid hydroperoxide (LOOH) which itself promotes formation of several additional peroxyl radicals. Helicobacter pylori mutant strains with disruptions in genes encoding the peroxiredoxins, alkyl hydroperoxide reductase (ahpC) and the bacterioferritin comigratory protein (bcp), were more sensitive than the parent strain to oxidizing agents. These mutant strains were particularly sensitive, compared to the wild type, to killing by the unsaturated fatty acid linolenic acid but were not sensitive to the saturated fatty acid palmitic acid. A double mutant strain (ahpC bcp) accumulated more than 3-fold more lipid peroxides than the parent strain, indicating these peroxiredoxins together play a role in detoxifying lipid peroxides. The level of free iron accumulation, a signature of oxidative stress damage, was correlated specifically to organic peroxide-mediated stress by both in vivo and in vitro approaches. Free iron accumulation and concomitant destruction of [Fe-S] cluster-containing proteins (hydrogenase and aconitase) was correlated to damage mediated by exogenous t-butyl peroxide, or separately to intracellular accumulation of lipid peroxides in mutant strains. A major macromolecular target of accumulating lipid peroxides in H. pylori is DNA, as mutant analysis approaches combined with quantitative DNA fragmentation studies and specific DNA damage assessment (i.e. 8-oxoguanine formation) were used to demonstrate that such damage was especially associated with ahpC and ahpC bcp strains.
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PMID:Lipid peroxidation as a source of oxidative damage in Helicobacter pylori: protective roles of peroxiredoxins. 1706 77

Visible light-driven redox reactions have been widely adopted for the production of chemicals to combat energy shortage and global warming. Key elements of such a reaction system include a photosensitizer, a catalyst, and an electron source. In this review, we introduce the small molecules and nanoparticles that are widely used as photosensitizers, as well as the development of a photosensitizer protein that is based on the expansion of genetic code, with a fluorescent protein that is used as a scaffold. Visible light-driven enzymes using proteins as photosensitizers or as catalysts such as carbon monoxide dehydrogenase (CODH), formic acid dehydrogenase (FDH), hydrogenase, nitrogenase, cytochrome P450 BM3, and alkane synthase are then described. CODH can be coupled with photosensitizing nanoparticles to reduce CO2 to CO, and hydrogenase can produce H2 using high-energy electrons produced from dye-sensitized nanoparticles. When water-soluble zinc porphyrin is coupled with FDH, visible light drives CO2 to produce formic acid. Nitrogenase can reduce N2 to NH3 using CdS nanoparticle as photosensitizer. Cytochrome P450 BM3 can be enhanced by a visible light-driven redox system and thus by hydroxylate lauric acid or fatty acids. CvFAP, an alkane synthase, can decarboxylate palmitic acid to pentadecane under blue light excitation. Moreover, we describe a genetically encoded photosensitive protein, which mimics the function of natural photosynthesis and catalyzes the conversion of CO2 to CO when covalently attached with a Ni-terpyridine complex.
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PMID:Coupling natural systems with synthetic chemistry for light-driven enzymatic biocatalysis. 3131 82