Title: Characterization of ferredoxin, flavodoxin, and rubredoxin from Clostridium formicoaceticum grown in media with high and low iron contents

Abstract

Ferredoxin, flavodoxin, and rubredoxin were purified to homogeneity from Clostridium formicoaceticum and characterized. Variation of the iron concentration of the growth medium caused substantial changes in the concentrations of ferredoxin and flavodoxin but not of rubredoxin. The ferredoxin has a molecular weight of 6000 and is a four iron-four sulfur protein with eight cysteine residues. The spectrum is similar to that of other ferredoxins. The molar extinction coefficients are 22.6 x 10/sup 3/ and 17.6 x 10/sup 3/ at 280 and 390 nm, respectively. From 100 g wet weight of cells grown with 3.6 ..mu..M iron and with 40 ..mu..M iron, 5 and 20 mg of ferredoxin were isolated, respectively. The molecular weight of rubredoxin is 5800 and it contains one iron and four cysteines. The UV-visible absorption spectrum is dissimilar to those of other rubredoxins in that the 373 nm absorption peak is quite symmetric, lacking the characteristic 350-nm shoulder found in other rubredoxins. The flavodoxin is a 14,500-molecular-weight protein which contains 1 mol of flavin mononucleotide per mol of protein. It forms a stable, blue semiquinone upon light irradiation in the presence of EDTA or during enzymatic reduction. When cells were grown in low-iron medium, flavodoxin constituted atmore » least 2% of the soluble cell protein; however, it was not detected in extracts of cells grown in high-iron medium. The rubredoxin and ferredoxin expressed during growth in low-iron and high-iron media are identical as judged by iron, inorganic sulfide, and amino acid analysis, as well as light absorption spectroscopy. 45 references.« less

Authors:

Ragsdale, S W; Ljungdahl, L G

Publication Date:

Sun Jan 01 00:00:00 EST 1984

Research Org.:

Univ. of Georgia, Athens

OSTI Identifier:

6005527

DOE Contract Number:  

AS09-79ER10499

Resource Type:

Journal Article

Journal Name:

J. Bacteriol.; (United States)

Additional Journal Information:

Journal Volume: 157:1

Country of Publication:

United States

Language:

English

Subject:

59 BASIC BIOLOGICAL SCIENCES; CLOSTRIDIUM; GROWTH; METABOLISM; FERREDOXIN; STRUCTURAL CHEMICAL ANALYSIS; ABSORPTION SPECTROSCOPY; ACETATES; AMINO ACIDS; BIOSYNTHESIS; CULTURE MEDIA; IRON; RESPONSE MODIFYING FACTORS; ULTRAVIOLET SPECTRA; BACTERIA; CARBOXYLIC ACID SALTS; CARBOXYLIC ACIDS; ELEMENTS; METALLOPROTEINS; METALS; MICROORGANISMS; ORGANIC ACIDS; ORGANIC COMPOUNDS; PROTEINS; SPECTRA; SPECTROSCOPY; SYNTHESIS; TRANSITION ELEMENTS; 550700* - Microbiology