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Hydrogenase enzymes. Hydrogenases. Anaerobic bacteria: -production of H 2 during fermentation of sugars -the use of H 2 in the reduction of CO 2 to methane or other compounds. -parallel hydogenase function of nitrogenase enzymes -H 2 as biological energy source. 1. Iron hydrogenases.
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Hydrogenases Anaerobic bacteria: -production of H2during fermentation of sugars -the use of H2 in the reduction of CO2 to methane or other compounds. -parallel hydogenase function of nitrogenase enzymes -H2 as biological energy source
1. Ironhydrogenases F cluster - Fe4S4+/2+ type, and ESR signal characteristic to the S=1/2 spin state in the reduced state of the enzyme. H cluster – hydrogen activation site; its oxidised form is ESR active.
1. Ironhydrogenases H2-oxidation 14Fe: 2F (F,F’), 1H Both H2 oxidation and production of H2 22Fe: 4F, 1H The redox potential of the F/S clusters of the C. Pasteurianum bacterium at pH ~ 8, and the mechanism of the hydrogenase II:
1. Ironhydrogenases The H cluster X-ray structure of the hydrogenase I enzyme of the C. Pasteurianum bacterium [Peters, J. W., Lanzilotta, W. N., Lemon, B. J. & Seefeldt, L. C. (1998) Science, 282, 1853–1858.]
1. Ironhydrogenases Schematic pictures of the hydrogen production and oxidation (A), and the direction of the electron transfer during reduction of the proton and oxidation of the H2 (B).
2. Nickel-ironhydrogenases +H2 Schematic drawing of the mechanism of the hydrogenase enzyme
2. Nickel-ironhydrogenases X-ray structure of the NiFe hidrogenase enzyme ofD. Gigas bacterium. On the right side the active centre of the enzyme is depicted, X = Fe, L1–3 = CN– and CO ligands, positions I and II indicate the H2 binding sites.
Bioinorganicchemistry of the C1 compounds Main steps of reduction of CO2 to methane, and the necessary cofactors. Binding sites of the C1 compounds are indicated by arrows in the formula of the cofactors.
1.Methylcoenzyme M reductase Assumed mechanism of the methyl-coenzyme M reductase enzyme
1.Methylcoenzyme M reductase Structure of F430 coenzyme
1.Methylcoenzyme M reductase The role of nickel in the reaction: 1. Binding of the substrate thioether or thiol groups. 2. Cleavage of the C–S bond (see Raney-Ni as desulfurilation catalyst). 3. Short life methyl binding site. 4. Oxidativ link of the sulfur atoms to disulfid.
2. CO-dehydrogenase = CO-oxidoreductase = Acethyl-CoA-synthase CO-dehydrogenase Acethyl-CoA-synthase
2. CO-dehydrogenase = CO-oxidoreductase = Acethyl-CoA-synthase Mechanism of the acethyl coenzyme A-synthase enzyme
2. CO-dehydrogenase = CO-oxidoreductase = Acethyl-CoA-synthase X-ray structure of the acethyl-coenzyme A synthase enzyme of the C. hydrogenoformans(A) and the schematic picture of the active centre with several bond lengths
Otherredoxienzymesin biologicalprocesses 1. Transformation of nucleotides: ribonucleotidereductaseenzymes
1. Transformation of nucleotides: ribonucleotide reductase X-ray structure of the active centre of class I (A) and III (B) bacterial RR enzymes
1. Transformation of nucleotides: ribonucleotide reductase The dinuclear iron centre of ribonucleotide reductase enzyme of E. Coli
2. Methanemonooxygenase Schematic mechanism of the sMMO enzyme
3. Oxotransferaseenzymes Schematic structure of the molybdopterine cofactor
3. Oxotransferaseenzymes Probable mechanism of the sulfite-oxidase enzyme
4. Alcohol-dehydrogenaseenzymes Structure and NADH binding site of the ADH enzyme of Pseudomonas aeruginosa
4. Alcohol-dehydrogenaseenzymes Active centre (the substrate analogue ethyleneglycole is bound to the zinc(II) ion) of the ADH enzyme of Pseudomonas aeruginosa . Protein Science (2004), 13:1547–1556.
