title: The tungsten-containing aldehyde oxidoreductase from Clostridium thermoaceticum and its complex with a viologen-accepting NADPH oxidoreductase.
abstract: Purification of aldehyde oxidoreductase from C. thermoaceticum, the first detected enzyme able to reduce reversibly non-activated carboxylic acids to the corresponding aldehydes (White, H., Strobl, G., Feicht, R. & Simon, H. (1989) Eur. J. Biochem. 184, 89-96), results in the generation of multiple forms of the enzyme. The specific activities for the viologen-mediated dehydrogenation of butyraldehyde for the two main forms of the purification procedure are 530 and 450 U/mg. Two forms of the enzyme composed of alpha,beta- and alpha,beta,gamma-subunits, can be differentiated. The latter binds to red-Sepharose and can be eluted very specifically with NADPH. In contrast to the alpha,beta-types the trimeric forms also catalyse the reversible reduction of oxidised viologen with NADPH (VAPOR activity). The dimer alpha,beta can oligomerize and the alpha,beta,gamma-trimer can easily form various oligomers or split off the gamma-subunit. The apparent molecular masses of the subunits alpha,beta and gamma are 64, 14 and 43 kDa. The alpha,beta-form reveals an apparent molecular mass of 86 kDa containing about 29 iron, 25 acid-labile sulphur, 0.8 tungsten and forms about 1 mol pterine-6-carboxylic acid by permanganate oxidation. The corresponding values of the trimer showing a mass of 300 kDa, are about 82 Fe, 54 S, 3.4 W and 2.5 pterine-6-carboxylic acid. In addition, 1.7 mol of FAD could be found which seems to be a component of the gamma-subunit. The aldehyde oxidoreductase from C. thermoaceticum and that from C. formicoaceticum (White, H., Feicht, R., Huber, C., Lottspeich, F. & Simon, H. (1991) Biol. Chem. Hoppe-Seyler 372, 999-1005) show qualitative similarities as far as the Fe, S, W and pterin content and the broad substrate specificity are concerned. However, there are also surprisingly marked differences with respect to composition and amino-acid sequence.
authors.affiliation: Lehrstuhl für Organische Chemie und Biochemie der Technischen Universität München.
authors.forename: G
authors.initials: G
authors.lastname: Strobl
authors.forename: R
authors.initials: R
authors.lastname: Feicht
authors.forename: H
authors.initials: H
authors.lastname: White
authors.forename: F
authors.initials: F
authors.lastname: Lottspeich
authors.forename: H
authors.initials: H
authors.lastname: Simon
mesh_terms: D000445:Aldehyde Oxidoreductases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D003013:Clostridium / Q000201:enzymology*; D004591:Electrophoresis, Polyacrylamide Gel; D015151:Immunoblotting; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009249:NADP / Q000378:metabolism; D013056:Spectrophotometry, Ultraviolet; D014414:Tungsten / Q000032:analysis; D014755:Viologens / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D014755:Viologens; D009249:NADP; D000445:Aldehyde Oxidoreductases; D014414:Tungsten