Harry D. Peck

Purification of the enzyme reducing bisulfite to trithionate from Desulfovibrio gigas and its identification as desulfoviridin

An enzyme which catalyzes the reductive formation of trithionate from sulfite is present in extracts of the sulfate reducing bacterium Desulfovibrio gigas and has been termed, bisulfite reductase. This activity has been purified and the enzyme identified as the green pigment, desulfoviridin, by gel electrophoresis and ultracentrifugation. The stoichiometry of the reduction of sulfite to trithionate is established and some physical properties of the enzyme reported.

The presence of multiple intrinsic membrane nickel-containing hydrogenases in Desulfovibrio vulgaris (hildenborough)

Three intrinsic membrane proteins exhibiting oxygen stable hydrogenase activity have been isolated from D. vulgaris. In contrast to the periplasmic exclusively non-heme iron hydrogenase, all three hydrogenases contain Ni in addition to non-heme iron, have low specific activities and are insensitive to inhibition by CO. None of the three hydrogenases cross react with IgA against the periplasmic hydrogenase of D. vulgaris but two of the new hydrogenases cross react with IgA against the periplasmic nickel containing hydrogenase of D. gigas and the other new hydrogenase cross reacts with IgA against the periplasmic nickel and selenium hydrogenase of D. desulfuricans (Norway -4).

Carboxy-terminal processing of the large subunit of [NiFe] hydrogenases

Two electrophoretic forms of the large subunit of the soluble periplasmic [NiFe] hydrogenase from Desulfovibrio gigas have been detected by Western analysis. The faster moving form co‐migrates with the large subunit from purified, active enzyme. Amino acid sequence and composition of the C‐terminal tryptic peptide of the large subunit from purified hydrogenase revealed that it is 15 amino acids shorter than that predicted by the nucleotide sequence. Processing of the nascent large subunit occurs by C‐terminal cleavage between His536 and Val537, residues which are highly conserved among [NiFe] hydrogenases. Mutagenesis of the analogous residues, His582 and Val583, in the E. coli hydrogenase‐1 (HYD1) large subunit resulted in significant decrease in processing and HYD1 activity.

The amino acid sequence of ferredoxin from the sulfate reducing bacterium, Desulfovibrio gigas

Abstract The primary structure of a ferredoxin from the sulfate reducing bacterium, Desulfovibrio gigas has been determined by conventional procedures. The molecule is unique among bacterial ferredoxins in that it contains only six cysteine residues, four in the first half and two in the second half of the sequence. Preliminary structural considerations suggest that it may be derived from a prototype ferredoxin intermediate between green plants and bacteria.

An iron tetrahydroporphyrin prosthetic group common to both assimilatory and dissimilatory sulfite reductases

The heme† chromophore of the “assimilatory” E. coli sulfite reductase is an iron-octacarboxylic tetrahydroporphyrin of the isobacteriochlorin type (1). Although the two “dissimilatory” sulfite reductases, desulfoviridin and desulforubidin, from the sulfate reducing bacteria Desulfovibrio gigas and Desulfovibrio desulfuricans (Norway strain), have absorption spectra and reaction products which differ from those of E. coli sulfite reductase, the present studies indicate that they contain prosthetic groups with an organic structure closely similar or identical to that of the E. coli sulfite reductase heme. EPR spectra show high-spin ferriheme in all three enzymes. It is clear, however, that the prosthetic groups must reside in substantially different environments within their respective proteins.

A flavin-sulfite adduct as an intermediate in the reaction catalyzed by adenylyl sulfate reductase from Desulfovibriovulgaris

Abstract A mechanism is postulated for adenylyl sulfate (APS) reductase, considered as the oxidation of sulfite to the level of sulfate (APS), which involves three steps in the absence of an added electron acceptor. The first step involves the reversible association of sulfite with enzyme-bound FAD to form a flavin-sulfite adduct; the second, a transfer of the sulfur moiety from FAD to a mononucleotide acceptor to yield the corresponding nucleotide 5′-phosphosulfate; and the third, the internal reduction of an as yet unknown chromophore to yield oxidized FAD.

Phosphorylation coupled to oxidation of hydrogen with fumarate in extracts of the sulfate reducing bacterium, Desulfovibrio gigas

Abstract The esterification of orthophosphate coupled to the oxidation of molecular hydrogen and concomitant reduction of fumarate to succinate is catalyzed by a particulate preparation from the anaerobic sulfate reducing bacterium, D. gigas. The system exhibits a P H 2 ratio of 0.3–0.4 and does not require the addition of soluble protein. The phosphorylation is uncoupled by gramicidin, pentachlorophenol, dinitrophenol and methyl viologen but not by oligomycin. The added fumarate was quantitatively reduced to succinate. It is suggested that phosphorylation coupled to electron transfer with the reduction of fumarate may be of general occurrence in anaerobic and facultative anaerobic bacteria.

IDENTIFICATION OF THREE CLASSES OF HYDROGENASE IN THE GENUS, DESULFOVIBRIO

A comparison of amino-terminal amino acid sequences from the large and small subunits of hydrogenases from Desulfovibrio reveals significant differences. These results, in conjunction with antibody analyses, clearly indicate that the iron, iron + nickel, and iron + nickel + selenium containing hydrogenases represent three distinct classes of hydrogenase in Desulfovibrio.

Flavoproteins, Iron Proteins, and Hemoproteins as Electron-Transfer Components of the Sulfate-Reducing Bacteria

Publisher Summary Sulfate-reducing bacteria essentially obtain their energy for growth from the oxidation of a limited number of organic acids, ethanol, or hydogen. The electrons derived from these substrates are used to reduce various sulfur compounds to the level of hydrogen sulfide. Sulfate-reducing bacteria are classified into two genera: (1) desulfotomaculum and (2) desulfovibrio. The former genus contains the spore-forming sulfate reducing bacteria and the thermophilic species. The sulfate-reducing bacteria contain four types of sulfite-reducing enzymes, which can be differentiated on the basis of their spectral properties, substrates, and products. Three of these enzymes appear to reduce bisulfite as their pH optimum is around 6.0; they have been termed bisulfite reductases. The reduction of bisulfite to sulfide occurs by one of two different mechanisms: (1) by direct six-electron reduction of bisulfite to sulfide catalyzed by bisulfite reductase or (2) by three successive two-electron reductions involving three different enzymes

The association of hydrogenase and dithionite reductase activities with the nitrite reductase of Desulfovibrio desulfuricans.

Summary The membrane bound respiratory nitrite reductase from Desulfovibrio desulfuricans contains six c-type heme groups and catalyzes the six electron reduction of nitrite to ammonia. The purified enzyme required an excess of reducing equivalents for reduction relative to the amount of nitrite consumed in its reoxidation. The anomaly could be accounted for in terms of the presence of low levels of dithionite reductase and hydrogenase activity in the preparation. Dithionite reductase may be an alternate activity of nitrite reductase, whereas hydrogenase was shown to be a contaminant. The contaminating hydrogenase used nitrite reductase as electron acceptor in preference to cytochrome c 3 (M r = 13,000) or benzyl viologen.