Methanogenic bacteria nickel

Methanococcus vanmelli formate dehydrogenases, 663 Methanococcus voltae cation transport, 558 Methanogenic bacteria nickel, 644 Methanogens energy, 643 Methanol carbonylation... 

Corphin is the F-430 cofactor found in methyl-coenzyme M reductase, a nickel-containing enzyme that participates in the conversion of carbon dioxide to methane in methanogenic bacteria. The nickel ion in F-430 is coordinated by the tetrahydrocorphin ligand, which contains structural elements of both porphyrins and corrins. 

Nickel is found in at least four enzymes urease, certain hydrogenases, methyl-CoM reductase (in its cofactor F430) of methanogenic bacteria, and carbon monoxide dehydrogenase of acetogenic and methanogenic bacteria 434... 

Nickel enzymes are particularly prominent in the metabolism of anaerobic bacteria. For example, the methanogenic bacteria, which are classified as Arch-aea, an ancient division of living organisms, can grow on a mixture of H2 and C02 to produce methane [9-11], The metabolism of methanogens involves three... 

The tetrapyrrole-type coenzyme F430 (19) was named on basis of its absorption maximum at 430 mn. The nickel-chelating factor is biosynthesized via the porphyrin biosynthetic pathway (Fig. 2) (19). For the handling of one-carbon fragments that play a central role in their metabolism, methanogenic bacteria use methanopterin (34, Fig. 3). The tetrahydropterine system that serves as the business end of the methanopterin coenzyme family is structurally similar to tetrahydrofolate, and the biosynthetic pathway starting from GTP is similar to that of tetrahydrofolate (Fig. 3). The ribitylaniline moiety is derived from ribose and from the shikimate pathway via 4-amino-benzoate (55). 

F-430 A tetrapyrrole structure containing nickel, a component of the ENZYME methyl-coenzyme M REDUCTASE, that is involved in the formation of methane in METHANOGENIC bacteria. The highly reduced macro-cyclic structure, related to porphyrins and corrins, is termed a corphin. 

Coenzyme F430, the hydrocorphinoid nickel(II) complex (Fig. 3) belongs to the unique group of coenzymes mediating the reduction of C02 to methane in methanogenic bacteria [8,9]. As a cofactor of methylcoenzyme M reductase it is involved in the reductive cleavage of S-methyl coenzyme M to coenzyme M and methane, an exergonic step coupled to the synthesis of ATP. 

Nickel occurs as a cofactor in four enzymes known to date (Walsh and Orme-Johnson, 1987). Ureases from plant and animal sources use two Ni atoms as Lewis acids, a role more typical of Zn. In the other three enzymes, all bacterial. Ni is redox active. In methyl coenzyme M reductase of methanogenic bacteria, Ni is found in a tetrapyrrole (factor F430) and cycles between Ni(ll) and Ni(l). Many bacteria contain Ni-dependent hydroge-nase(s) and methanogenic and acetogenic bacteria have a specific Ni-containing CO... 

Our knowledge of the stereochemistry of porphyrins and related tetrapyrrole macrocycles has expanded rapidly since the first reported x-ray structure determination in 1959 The structures of metallotetrapyrrole complexes are of interest because of the common occurrence of this type of macrocycle in biological systems. As is well known, foremost among these are the heme proteins (iron derivatives), the various photosynthetic pigments (magnesium complexes), the vitamin Bn coenzyme (cobalt corrinoids), and coenzyme F430 (nickel corphinoids) of the methanogenic bacteria. 

The nickel-containing factor F 430 (134) provides an example of how nature exploits the reactivity of organometallic compounds, as is the case with vitamin B12. Factor F 430 (134) plays a key role as cofactor for the coenzyme M reductase of primitive methanogenic bacteria in the formation of methane from 2-(methylthio)-ethanesulfonate (86). The structural elucidation of factor F 430 (134) is based on a combination of classical spectroscopic methods, chemical degradation, and biosynthetic studies with C-labelled precursors 83a,b). These biosynthetic investigations will be addressed in section 8.2. Chemical degradation products obtained by ozonolysis of factor F 430 (134) allowed the determination of the absolute configuration by comparison with reference compounds derived from chlorophyll a (2) and vitamin B12 (4) 83a,b). 

The largest body of work is devoted to nickel (II) F-430, the hydrocorphin cofactor of methyl coenzyme M reductase from methanogenic bacteria... 

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