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)

The particulate hydrogenase of Vibrio succinogenes is solubilized during treatment of cell envelopes at pH 11.0. Alkali-solubilized enzyme requires sulfhydryl compounds for activity. At neutral pH, soluble enzyme is reincorporated into alkalitreated cell envelopes and no longer requires an additional activator. In the present study, cell envelopes prepared by lysing cells with ethylenediaminetetraacetic acid plus lysozyme (EDTA-lysozyme) were used to determine the chemical composition of cell envelopes and derived pH 11.0 soluble and insoluble fractions and to investigate some properties of the binding and activation of alkali-solubilized hydrogenase. Lysis with EDTA-lysozyme resulted in the formation of spheroplast ghosts. The derived cell envelopes contained 61% protein, 3% ash, 23% lipid, and 1% phosphorus. The alkali-treated cell envelopes contained 50% protein, 2% ash, 24% lipid, and 1% phosphorus. The ash from cell envelopes and alkali-treated cell envelopes was rich in iron and phosphorus and also contained calcium, copper, magnesium, sodium, and zinc. Virtually all of the weight of the ashed samples was accounted for by the oxides of these metals. Since the reconstitution of particulate hydrogenase was achieved with pH 11.0 supernatant solution and precipitate, intact mucopeptide is not essential for hydrogenase binding. Release of hydrogenase during EDTA-lysozyme lysis was found to depend upon an apparent structural change which occurs in the membranes during extended storage at -20 C.
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PMID:Chemical constituents and hydrogenase binding in cell envelopes of Vibrio succinogenes. 497 63

Various dehydrogenases, reductases, and electron transfer proteins involved in respiratory sulfate reduction by Desulfovibrio gigas have been localized with respect to the periplasmic space, membrane, and cytoplasm. This species was grown on a lactate-sulfate medium, and the distribution of enzyme activities and concentrations of electron transfer components were determined in intact cells, cell fractions prepared with a French press, and lysozyme spheroplasts. A significant fraction of formate dehydrogenase was demonstrated to be localized in the periplasmic space in addition to hydrogenase and some c-type cytochrome. Cytochrome b, menaquinone, fumarate reductase, and nitrite reductase were largely localized on the cytoplasmic membrane. Fumarate reductase was situated on the inner aspect on the membrane, and the nitrite reductase appeared to be transmembraneous. Adenylylsulfate reductase, bisulfite reductase (desulfoviridin), pyruvate dehydrogenase, and succinate dehydrogenase activities were localized in the cytoplasm. Significant amounts of hydrogenase and c-type cytochromes were also detected in the cytoplasm. Growth of D. gigas on a formate-sulfate medium containing acetate resulted in a 10-fold increase in membrane-bound formate dehydrogenase and a doubling of c-type cytochromes. Growth on fumarate with formate resulted in an additional increase in b-type cytochrome compared with lactate-sulfate-grown cells.
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PMID:Localization of dehydrogenases, reductases, and electron transfer components in the sulfate-reducing bacterium Desulfovibrio gigas. 724 92

Entamoeba histolytica is a protozoan parasite that causes colitis and liver abscesses. Several Entamoeba species and strains with differing levels of virulence have been identified. E. histolytica HM-1:IMSS is a virulent strain, E. histolytica Rahman is a nonvirulent strain, and Entamoeba dispar is a nonvirulent species. We used an E. histolytica DNA microarray consisting of 2,110 genes to assess the transcriptional differences between these species/strains with the goal of identifying genes whose expression correlated with a virulence phenotype. We found 415 genes expressed at lower levels in E. dispar and 32 genes with lower expression in E. histolytica Rahman than in E. histolytica HM-1:IMSS. Overall, 29 genes had decreased expression in both the nonvirulent species/strains than the virulent E. histolytica HM-1:IMSS. Interestingly, a number of genes with potential roles in stress response and virulence had decreased expression in either one or both nonvirulent Entamoeba species/strains. These included genes encoding Fe hydrogenase (9.m00419), peroxiredoxin (176.m00112), type A flavoprotein (6.m00467), lysozyme (6.m00454), sphingomyelinase C (29.m00231), and a hypothetical protein with homology to both a Plasmodium sporozoite threonine-asparagine-rich protein (STARP) and a streptococcal hemagglutinin (238.m00054). The function of these genes in Entamoeba and their specific roles in parasite virulence need to be determined. We also found that a number of the non-long-terminal-repeat retrotransposons (EhLINEs and EhSINEs), which have been shown to modulate gene expression and genomic evolution, had lower expression in the nonvirulent species/strains than in E. histolytica HM-1:IMSS. Our results, identifying expression profiles and patterns indicative of a virulence phenotype, may be useful in characterizing the transcriptional framework of virulence.
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PMID:Identification of differentially expressed genes in virulent and nonvirulent Entamoeba species: potential implications for amebic pathogenesis. 1636 89

Water splitting into oxygen and hydrogen is one of the most attractive strategies for storing solar energy and electricity. Because the processes at work are multielectronic, there is a crucial need for efficient and stable catalysts, which in addition have to be cheap for future industrial developments (electrolyzers, photoelectrochemicals, and fuel cells). Specifically for the water/hydrogen interconversion, Nature is an exquisite source of inspiration since this chemistry contributes to the bioenergetic metabolism of a number of living organisms via the activity of fascinating metalloenzymes, the hydrogenases. In this Account, we first briefly describe the structure of the unique dinuclear organometallic active sites of the two classes of hydrogenases as well as the complex protein machineries involved in their biosynthesis, their so-called maturation processes. This knowledge allows for the development of a fruitful bioinspired chemistry approach, which has already led to a number of interesting and original catalysts mimicking the natural active sites. More specifically, we describe our own attempts to prepare artificial hydrogenases. This can be achieved via the standard bioinspired approach using the combination of a synthetic bioinspired catalyst and a polypeptide scaffold. Such hybrid complexes provide the opportunity to optimize the system by manipulating both the catalyst through chemical synthesis and the protein component through mutagenesis. We also raise the possibility to reach such artificial systems via an original strategy based on mimicking the enzyme maturation pathways. This is illustrated in this Account by two examples developed in our laboratory. First, we show how the preparation of a lysozyme-{Mn(I)(CO)3} hybrid and its clean reaction with a nickel complex led us to generate a new class of binuclear Ni-Mn H2-evolving catalysts mimicking the active site of [NiFe]-hydrogenases. Then we describe how we were able to rationally design and prepare a hybrid system, displaying remarkable structural similarities to an [FeFe]-hydrogenase, and we show here for the first time that it is catalytically active for proton reduction. This system is based on the combination of HydF, a protein involved in the maturation of [FeFe]-hydrogenase (HydA), and a close mimic of the active site of this class of enzymes. Moreover, the synthetic [Fe2(adt)(CO)4(CN)2](2-) (adt(2-)= aza-propanedithiol) mimic, alone or within a HydF hybrid system, was shown to be able to maturate and activate a form of HydA itself lacking its diiron active site. We discuss the exciting perspectives this "synthetic maturation" opens regarding the "invention" of novel hydrogenases by the chemists.
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PMID:From enzyme maturation to synthetic chemistry: the case of hydrogenases. 2616 93