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)

Two soluble hydrogenase activities were separable from cell extracts of the cyanobacterium Anabaena cylindrica, one detectable by the tritium exchange assay, the other having a relatively low tritium exchange activity but catalyzing methyl viologen-dependent hydrogen formation. Their molecular weights, by gel filtration chromatography, were 42,000 and 100,000, respectively. The two hydrogenase activities were differentially inhibited. The methyl viologen-dependent activity has been purified to homogeneity from cells in which the enzyme was induced by gassing the growing cells with N2/H2/CO2 (95.7%/4%/0.3%, v/v/v). The procedure involved French pressure cell disruption of the cells, differential precipitation with ZnCl2, heat treatment (50 degrees C), and lyophilization of the heat-step supernatant. It was then subjected to DEAE-Sephacel chromatography, dye-ligand chromatography on Procion Red, and HPLC anion exchange on QMA-Accel. Polyacrylamide gel electrophoresis on both native and denaturing gels revealed two peptides with Mr's 42,000 and 50,000. The 42,000 protein alone catalyzed tritium exchange activity; both proteins appeared to be necessary for the methyl viologen activity. The native enzyme appears to be a readily dissociable dimer of two nonidentical subunits, one of which contains the hydrogen binding site and the other providing the ability to utilize electrons from a reductant for hydrogen formation.
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PMID:Purification and properties of soluble hydrogenase from the cyanobacterium Anabaena cylindrica. 249 82

An inactive, Ni-deficient form of carbon monoxide (CO) dehydrogenase [carbon-monoxide:(acceptor) oxidoreductase; EC 1.2.99.2], designated apo-CO dehydrogenase, accumulated in Rhodospirillum rubrum when cells were grown in the absence of Ni and treated with CO. In vivo, both CO dehydrogenase activity and hydrogenase activity increased several hundred fold upon addition of 2 microM NiCl2. Apo-CO dehydrogenase was purified to homogeneity and differed from holo-CO dehydrogenase only in its activity and Ni content, containing less than 0.2 mol of Ni per mol of protein, and a specific activity of 35 mumol of CO per min per mg. Optimal in vitro activation of purified apo-CO dehydrogenase resulted in an enzyme with a specific activity of 2640 mumol of CO per min per mg. No additional enzymes or low molecular weight cofactors were required for activation. Apo-CO dehydrogenase was not activated by MgCl2, MnCl2, CuCl2, ZnCl2, CoCl2, or Na2MoO4. 63Ni was incorporated into apo-CO dehydrogenase during activation. The electron paramagnetic resonance (EPR) spectra of dithionite-reduced apo- and holo-enzyme were identical, indicating that, in the reduced state, the Fe-S centers observed by EPR are unchanged in the apo-enzyme.
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PMID:Nickel-deficient carbon monoxide dehydrogenase from Rhodospirillum rubrum: in vivo and in vitro activation by exogenous nickel. 282 76