title: Purification and characterization of a ferredoxin from acetate-grown Methanosarcina thermophila.
abstract: A ferredoxin, which functions as an electron acceptor for the CO dehydrogenase complex from Methanosarcina thermophila, was purified from acetate-grown cells. It was isolated as a trimer having a native molecular weight of approximately 16,400 and monomer molecular weight of 4,888 calculated from the amino acid composition. The ferredoxin contained 2.80 +/- 0.56 Fe atoms and 1.98 +/- 0.12 acid-labile sulfide. UV-visible absorption maxima were 395 and 295 nm with monomeric extinction coefficients of epsilon 395 = 12,800 M-1 cm-1 and epsilon 295 = 14,460 M-1 cm-1. The A395/A295 ratio ranged from 0.80 to 0.88. There were 5 cysteines per monomer but no methionine, histidine, arginine, or aromatic amino acids. The N-terminal amino acid sequence showed a 4-cysteine cluster with potential to coordinate a Fe:S center. The protein was stable for 30 min at 70 degrees C, but denatured during incubation at 85 degrees C.
authors.affiliation: Department of Anaerobic Microbiology, Virginia Polytechnic Institute and State University, Blacksburg 24061.
authors.forename: K C
authors.initials: KC
authors.lastname: Terlesky
authors.forename: J G
authors.initials: JG
authors.lastname: Ferry
mesh_terms: D000085:Acetates / Q000378:metabolism*; D019342:Acetic Acid; D000595:Amino Acid Sequence; D019605:Euryarchaeota / Q000032:analysis*; D005288:Ferredoxins / Q000302:isolation & purification*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011489:Protein Denaturation; D013056:Spectrophotometry, Ultraviolet
chemical_list: D000085:Acetates; D005288:Ferredoxins; D019342:Acetic Acid