title: A four-iron, four-sulfide ferredoxin with high thermostability from Clostridium thermoaceticum.
abstract: A ferredoxin containing only one [Fe4S4] cluster was purified from Clostridium thermoaceticum. It has a molecular weight of about 7,300, a partial specific volume of 0.67, and an isoelectric point of 3.25. Its absorption spectrum has two maxima at 390 nm (epsilon = 16.8 X 10(3)M-1cm-1) and at 280 nm (epsilon = 24.2 X 10(3)M-1cm-1). The absorption at 390 nm is almost half that of other clostridial ferredoxins, which have two [Fe4S4] clusters, and is similar to other ferredoxins with only one [Fe4S4] cluster. The ferredoxin had high thermal stability and retained over 50% of its activity after treatment at 80 degrees C. It functions in the transfer of electrons from pyruvate to nicotinamide adenine dinucleotide phosphate (NADP), which indicates the presence of pyruvate:ferredoxin oxidoreductase and reduced ferredoxin-NADP reductase in C, thermoaceticum. NADPH is used in the synthesis of acetate from CO2 in this organism.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D003013:Clostridium / Q000032:analysis* / Q000378:metabolism; D005288:Ferredoxins / Q000302:isolation & purification* / Q000378:metabolism; D006358:Hot Temperature; D007501:Iron / Q000032:analysis; D007526:Isoelectric Point; D008722:Methods; D008970:Molecular Weight; D011489:Protein Denaturation; D011773:Pyruvates / Q000378:metabolism; D013053:Spectrophotometry; D013440:Sulfides / Q000032:analysis
chemical_list: D000596:Amino Acids; D005288:Ferredoxins; D011773:Pyruvates; D013440:Sulfides; D007501:Iron