Publications

• Nicotinamide adenine dinucleotide phosphate-dependent formate dehydrogenase from Clostridium thermoaceticum: purification and properties.

  Andreesen J.R., Ljungdahl L.G.

  The nicotinamide adenine dinucleotide phosphate (NADP)-dependent formate dehydrogenase in Clostridium thermoaceticum used, in addition to its natural electron acceptor, methyl and benzyl viologen. The enzyme was purified to a specific activity of 34 (micromoles per minute per milligram of protein) ... >> More

  The nicotinamide adenine dinucleotide phosphate (NADP)-dependent formate dehydrogenase in Clostridium thermoaceticum used, in addition to its natural electron acceptor, methyl and benzyl viologen. The enzyme was purified to a specific activity of 34 (micromoles per minute per milligram of protein) with NADP as electron acceptor. Disc gel electrophoresis of the purified enzyme yielded two major and two minor protein bands, and during centrifugation in sucrose gradients two components of apparent molecular weights of 270,000 and 320,000 were obtained, both having formate dehydrogenase activity. The enzyme preparation catalyzed the reduction of riboflavine 5'-phosphate flavine adenine dinucleotide and methyl viologen by using reduced NADP as a source of electrons. It also had reduced NADP oxidase activity. The enzyme was strongly inhibited by cyanide and ethylenediaminetetraacetic acid. It was also inhibited by hypophosphite, an inhibition that was reversed by formate. Sulfite inhibited the activity with NADP but not with methyl viologen as acceptor. The apparent K(m) at 55 C and pH 7.5 for formate was 2.27 x 10(-4) M with NADP and 0.83 x 10(-4) with methyl viologen as acceptor. The apparent K(m) for NADP was 1.09 x 10(-4) M and for methyl viologen was 2.35 x 10(-3) M. NADP showed substrate inhibition at 5 x 10(-3) M and higher concentrations. With NADP as electron acceptor, the enzyme had a broad pH optimum between 7 and 9.5. The apparent temperature optimum was 85 C. In the absence of substrates, the enzyme was stable at 70 C but was rapidly inactivated at temperatures above 73 C. The enzyme was very sensitive to oxygen but was stabilized by thiol-iron complexes and formate. << Less

  J Bacteriol 120:6-14(1974) [PubMed] [EuropePMC]

• Purification and properties of NADP-dependent formate dehydrogenase from Clostridium thermoaceticum, a tungsten-selenium-iron protein.

  Yamamoto I., Saiki T., Liu S.M., Ljungdahl L.G.

  NADP-dependent formate dehydrogenase (NADP+) (EC 1.2.1.43) from Clostridium thermoaceticum has been purified to a specific activity of about 1100 mumol min-1 mg-1 when assayed at 55 degrees C and pH 7.5. The enzyme is extremely oxygen-sensitive and 7.6 microM of O2 causes 50% inhibition of initial ... >> More

  NADP-dependent formate dehydrogenase (NADP+) (EC 1.2.1.43) from Clostridium thermoaceticum has been purified to a specific activity of about 1100 mumol min-1 mg-1 when assayed at 55 degrees C and pH 7.5. The enzyme is extremely oxygen-sensitive and 7.6 microM of O2 causes 50% inhibition of initial velocity under assay conditions. Purification was done in an atmosphere at 95% N2 and 5% H2 and by including azide, dithionite, and glycerol as stabilizing agents in all buffer solutions. The enzyme contains, in molar ratios, 2 tungsten, 2 selenium, 36 iron, and about 50 inorganic sulfur. It has a molecular weight of about 340,000 and consist of two each of two different subunits giving the composition alpha 2 beta 2. The molecular weight of the alpha-subunit is 96,000 and that of the beta-subunit is 76,000. The selenium resides in the two alpha-subunits. Tungsten is released from the protein on denaturation and may exist as a tungsten cofactor. The enzyme catalyzes a reduction of CO2 with NADPH at pH 7.5 and 55 degrees C and Keq at these conditions is (2.35 +/-0.49) x 10(-2) if CO2 is considered the active species and (1.48 +/-0.31) x 10(-3) if HCO3- is the active species. << Less

  J Biol Chem 258:1826-1832(1983) [PubMed] [EuropePMC]