PERIPLASMIC SULFIDE DEHYDROGENASE (SUD) FROM WOLINELLA-SUCCINOGENES - ISOLATION, NUCLEOTIDE-SEQUENCE OF THE SUD GENE AND ITS EXPRESSION IN ESCHERICHIA-COLI

Wolinella succinogenes contains a periplasmic sulphide dehydrogenase when grown with formate and polysulphide as catabolic substrates. The isolated enzyme catalyzes the reduction of dimethylnaphthoquinone with sulphide at high values of both apparent K-m and turnover number. The active enzyme consists of two identical subunits (14 kDa) and amounts to approximately 1% of the soluble cell protein. Prosthetic groups such as flavin, haem or molybdenum are missing. The corresponding gene (sud) encodes a signal peptide together with the mature subunit that consists of 129 amino acid residues including one single cysteine. The sud gene is expressed from a plasmid in Escherichia coli. The resulting enzyme catalyzes sulphide oxidation with dimethylnaphthoquinone and is located in the periplasm of E. coli.