Methyl (Alkyl)-Coenzyme M Reductases: Nickel F-430-Containing Enzymes Involved in Anaerobic Methane Formation and in Anaerobic Oxidation of Methane or of Short Chain Alkanes.

Methyl-coenzyme M reductase (MCR) catalyzes the methane-forming step in methanogenic archaea. The active enzyme harbors the nickel(I) hydrocorphin coenzyme F-430 as a prosthetic group and catalyzes the reversible reduction of methyl-coenzyme M (CH-S-CoM) with coenzyme B (HS-CoM) to methane and CoM-S-S-CoB. MCR is also involved in anaerobic methane oxidation in reverse of methanogenesis and most probably in the anaerobic oxidation of ethane, propane, and butane.

Flavin-Based Electron Bifurcation, Ferredoxin, Flavodoxin, and Anaerobic Respiration With Protons (Ech) or NAD (Rnf) as Electron Acceptors: A Historical Review.

Flavin-based electron bifurcation is a newly discovered mechanism, by which a hydride electron pair from NAD(P)H, coenzyme FH, H, or formate is split by flavoproteins into one-electron with a more negative reduction potential and one with a more positive reduction potential than that of the electron pair. Via this mechanism microorganisms generate low- potential electrons for the reduction of ferredoxins (Fd) and flavodoxins (Fld). The first example was described in 2008 when it was found that the butyryl-CoA dehydrogenase-electron-transferring flavoprotein complex (Bcd-EtfAB) of couples the endergonic reduction of ferredoxin (E' = -420 mV) with NADH (-320 mV) to the exergonic reduction of crotonyl-CoA to butyryl-CoA (-10 mV) with NADH.

Flavin-Based Electron Bifurcation, A New Mechanism of Biological Energy Coupling.

There are two types of electron bifurcation (EB), either quinone- or flavin-based (QBEB/FBEB), that involve reduction of a quinone or flavin by a two-electron transfer and two reoxidations by a high- and low-potential one-electron acceptor with a reactive semiquinone intermediate. In QBEB, the reduced low-potential acceptor (cytochrome b) is exclusively used to generate ΔμH. In FBEB, the "energy-rich" low-potential reduced ferredoxin or flavodoxin has dual function.

Lothar Jaenicke and C1-metabolism: his first 25 years of research.

The biochemist Lothar Jaenicke died on 29 December 2015, aged 92 years old. The last time I saw him was at his 90th birthday on 14 September 2013, at the occasion of which his colleagues at the Universität zu Köln (Cologne) in Germany had organized a symposium to honor him.

Diversity of bacteria and archaea from two shallow marine hydrothermal vents from Vulcano Island.

To obtain new insights into community compositions of hyperthermophilic microorganisms, defined as having optimal growth temperatures of 80 °C and above, sediment and water samples were taken from two shallow marine hydrothermal vents (I and II) with temperatures of 100 °C at Vulcano Island, Italy. A combinatorial approach of denaturant gradient gel electrophoresis (DGGE) and metagenomic sequencing was used for microbial community analyses of the samples. In addition, enrichment cultures, growing anaerobically on selected polysaccharides such as starch and cellulose, were also analyzed by the combinatorial approach.