Membrane-bound formate dehydrogenase (FDH) was purified to homogeneity from a facultative anaerobic bacterium Citrobacter sp. S-77. The FDH from Citrobacter sp. S-77 (FDHS77) was a monomer with molecular mass of approximately 150kDa. On SDS-PAGE, the purified FDHS77 showed as three different protein bands with molecular mass of approximately 95, 87, and 32kDa, respectively. Based on the N-terminal amino acid sequence analysis, the sequence alignments observed for the 87kDa protein band were identical to that of the large subunit of 95kDa, indicating that the purified FDHS77 consisted of two subunits; a 95kDa large subunit and a 32kDa small subunit. The purified FDHS77 in this purification did not contain a heme b subunit, but the FDHS77 showed significant activity for formate oxidation, determined by the Vmax of 30.4U/mg using benzyl viologen as an electron acceptor. The EPR and ICP-MS spectra indicate that the FDHS77 is a molybdenum-containing enzyme, displaying a remarkable O2-stability along with thermostability and pH resistance. This is the first report of the purification and characterization of a FDH from Citrobacter species.
All Science Journal Classification (ASJC) codes
- Applied Microbiology and Biotechnology