Coenzym F430 aus Methan-Bakterien: Zusammenhänge zwischen der Struktur des hydroporphinoiden Liganden und der Redoxchemie des Nickelzentrums

Abstract

The hydroporphinoid nickel complex coenzyme F430 ist the prosthetic group of methyl-coenzyme M reductase, the enzyme catalyzing the last step of biological methane formation. Although the enzyme mechanism is still unknown, it has been shown that the isolated cofactor can be reduced to the Ni^I-form at surprisingly positive potentials. Recent in vivo EPR studies indicate that the Ni^I form of F430 is indeed formed in whole cells and in highly active enzyme preparations. A comparative study of the redox chemistry of partially synthetic derivatives of F430 helped to identify the structural elements that allow coenzyme F430 to be reduced at the metal rather than at the ligand and at a physiologically accessible potential.