tailieunhanh - Báo cáo khóa học: Tungsten-containing aldehyde oxidoreductase of Eubacterium acidaminophilum

Aldehyde oxidoreductase ofEubacterium acidaminophilum was purified to homogeneity under strict anaerobic condi-tions using a four-step procedure. The purified enzyme was present as a monomer with an apparent molecular mass of 67 kDa and contained ± iron, ± tungsten, about mol pterincofactor andzinc, but nomolybdenum. The enzymeactivitywas induced if amolar excessof electron donors, such as serine and/or formate, were supplied in the growth medium compared to readily available electron acceptors such as glycine betaine | Eur. J. Biochem. 271 212-219 2004 FEBS 2003 doi Tungsten-containing aldehyde oxidoreductase of Eubacterium acidaminophilum Isolation characterization and molecular analysis David Rauh Andrea Graentzdoerffer Katrin Granderath Jan R. Andreesen and Andreas Pich Institut fur Mikrobiologie Martin-Luther-Universitdt Halle-Wittenberg Halle Germany Aldehyde oxidoreductase of Eubacterium acidaminophilum was purified to homogeneity under strict anaerobic conditions using a four-step procedure. The purified enzyme was present as a monomer with an apparent molecular mass of 67 kDa and contained n on. tgngsten about mol pterin cofactor and zinc but no molybdenum. The enzyme activity was induced if a molar excess of electron donors such as serine and or formate were supplied in the growth medium compared to readily available electron acceptors such as glycine betaine. Many aldehydes served as good substrates thus enzyme activity obtained with acetaldehyde propionaldehyde butyraldehyde isovaleraldehyde and benzaldehyde differed by a factor of less than two. Kinetic parameters were determined for all substrates tested. Oligonucleotides deduced from the N-terminal amino acid sequence were used to isolate the encoding aorA gene and adjacent DNA regions. The deduced amino acid sequence of the aldehyde oxidoreductase exhibited high similarities to other tungsten-containing aldehyde oxidoreductases from archaea. Transcription of the aorA gene was monocistronic and started from a ơ54-dependent promoter. Upstream of aorA the gene aorR is localized whose product is similar to ơ54-dependent transcriptional activator proteins and thus AorR is probably involved in the regulation of aorA expression. Keywords aldehyde oxidoreductase tungsten pyranopterin cofactor transcriptional regulation Eubacterium acidamino-philum. Tungsten is a rather rare element 1 and the element with the largest mass positively involved in living systems. In recent .