title: Thermoacidophilic archaebacteria contain bacterial-type ferredoxins acting as electron acceptors of 2-oxoacid:ferredoxin oxidoreductases.
abstract: Thermoplasma acidophilum and Sulfolobus acidocaldarius contain coenzyme A-acylating 2-oxoacid:ferredoxin oxidoreductases similar to those found in halophilic archaebacteria. A common feature of these enzymes is the formation of a free radical intermediate in the course of the catalytic cycle. The electron-accepting ferredoxins and a similar protein from Desulfurococcus mobilis have been purified and characterized. In contrast to the [2Fe-2S] ferredoxin of Halobacterium halobium, the ferredoxins of thermoacidophilic archaebacteria most likely contain two [4Fe-4S]2 + (2 + .1 +) clusters per molecule. Properties of these proteins are compared with respect to the evolution of archaebacteria.
mesh_terms: D000596:Amino Acids / Q000302:isolation & purification; D001105:Archaea / Q000201:enzymology*; D001419:Bacteria / Q000201:enzymology*; D004579:Electron Transport; D005288:Ferredoxins / Q000502:physiology*; D005609:Free Radicals; D006217:Halobacterium / Q000201:enzymology; D007658:Ketone Oxidoreductases / Q000378:metabolism*; D010084:Oxidation-Reduction; D050743:Pyruvate Synthase; D013822:Thermoplasma / Q000201:enzymology
chemical_list: D000596:Amino Acids; D005288:Ferredoxins; D005609:Free Radicals; D007658:Ketone Oxidoreductases; D050743:Pyruvate Synthase; C023096:2-oxoglutarate synthase