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)

We have investigated the effect of added selenite on autotrophic growth and the time course of hydrogen oxidation derepression in Bradyrhizobium japonicum 122DES cultured in a medium purified to remove selenium compounds. In addition, hydrogenase was purified to near homogeneity and examined for the specific incorporation of Se into the enzyme. The addition of Se at 0.1 microM significantly increased total cell protein and hydrogenase specific activity of harvested cells. Also, the addition of SeO3(2-) enhanced the time course of hydrogenase derepression by 133%, whereas VO3, AsO2(2-), SO2(2-), and TeO3(2-) failed to substantially affect hydrogenase derepression. During the final chromatographic purification of hydrogenase, a striking coincidence in peaks of protein content, Se radioactivity, and hydrogenase activity of fractions was obtained. The total Se content expressed per milligram of protein increased manyfold during the purification procedure. The mean Se content of the purified hydrogenase was 0.56 +/- 0.13 mol of Se per mol of enzyme. These results indicate that Se is an important element in the H2 metabolism of B. japonicum and that hydrogenase from B. japonicum is a seleno protein.
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PMID:Selenium increases hydrogenase expression in autotrophically cultured Bradyrhizobium japonicum and is a constituent of the purified enzyme. 305 5

The active site of [NiFe] hydrogenase is a binuclear metal complex composed of Fe and Ni atoms and is called the Ni-Fe site, where the Fe atom is known to be coordinated to three diatomic ligands. Two mass spectrometric techniques, pyrolysis-MS (pyrolysis-mass spectrometry) and TOF-SIMS (time-of-flight secondary ion mass spectrometry), were applied to several proteins, including native and denatured forms of [NiFe] hydrogenase from Desulfovibrio vulgaris Miyazaki F, [Fe4S4]2-ferredoxin from Clostridium pasteurianum, [Fe,S2]-ferredoxin from Spirulna platensis, and porcine pepsin. Pyrolysis-MS revealed that only native hydrogenase liberated SO/SO2 (ions of m/z 48 and 64 at an equilibrium ratio of SO and SO2) at relatively low temperatures before the covalent bonds in the polypeptide moiety started to decompose. TOF-SIMS indicated that native Miyazaki hydrogenase released SO/SO2 (m/z 47.97 and 63.96) as secondary ions when irradiated with a high-energy Ga+ beam. Denatured hydrogenase, clostridial ferredoxin, and pepsin did not release SO as a secondary ion. The FT-IR spectrum of the enzyme suggested the presence of CO and CN. These lines of evidence suggest that the three diatomic ligands coordinated to the Fe atom at the Ni-Fe site in Miyazaki hydrogenase are SO, CO, and CN. The role of the SO ligand in helping to cleave H2 molecules at the active site and stabilizing the Fe atom in the diamagnetic Fe(II) state in the redox cycle of this enzyme is discussed.
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PMID:The presence of a SO molecule in [NiFe] hydrogenase from Desulfovibrio vulgaris Miyazaki as detected by mass spectrometry. 1100 Oct 90