PURIFICATION AND CHARACTERIZATION OF FERREDOXIN FROM PEPTOSTREPTOCOCCUS-PRODUCTUS (STRAIN MARBURG)

Abstract

Ferredoxin was purified to apparent homogeneity from cell extracts of the homoacetogen Peptostreptococcus productus (strain Marburg). The yield was 70-mu-g ferredoxin per g wet cells of P. productus. The UV-vis spectrum exhibited characteristics of a typical clostridial ferredoxin spectrum with a molar extinction coefficient epsilon-385 of approximately 30 000 M-1 cm-1 and an A385/A280 ratio of 0.76. The molecular weight M(r) was near 5700 as calculated from the amino acid composition. The protein contained per mol 9.9 mol iron, 8.2 mol acid-labile sulfide, and near 7 mol cysteine indicating the presence of two 4 Fe/4 S clusters. The redox potential was determined to be -410 mV. The purified ferredoxin was reduced with carbon monoxide by the carbon monoxide dehydrogenase from crude extracts and by the partially enriched enzyme of P. productus.