Purification and characterization of three proteins from a halophilic sulfate-reducing bacterium, Desulfovibrio salexigens

Summary Hydrogenase, desulfoviridin and molybdenum proteins have been isolated from a halophilic sulfate-reducing bacteria,Desulfovibrio salexigens strain British Guiana. At least 50% of the hydrogenase was found to be located in the periplasm. The hydrogenase has a typical absorption spectrum, a 400/280 nm ratio of 0.28, a molecular weight by sedimentation equilibrium of 81 000 and is composed of two subunits. It has one nickel, one selenium and 12 iron atoms per molecule. The sulfite reductase has a typical desulfoviridin absorption spectrum, a molecular weight of 191 000 and iron and zinc associated with it. The molybdenum-iron protein is gray-green in color and exhibits an absorbtion spectrum with peaks around 612, 410, 275 nm and a shoulder at 319 nm. It is composed of subunits of approximately 13 250 and has an approximate molecular weight of 110 000. Three molybdenum and 20 iron atoms are found associated with it.