Reduced Flavin Adenine Dinucleotide Research Articles

Purification and properties of trimethylamine oxide reductase from Salmonella typhimurium.

The major inducible trimethylamine oxide reductase was purified from Salmonella typhimurium LT2. The molecular weights of the native enzyme were estimated to be 332,000 by gel filtration and 170,000 by nondenaturing disc gel electrophoresis. In sodium dodecyl sulfate-gel electrophoresis, the enzyme formed a single band of molecular weight 84,000. The isoelectric point was 4.28. Maximum activity was at pH 5.65 and 45 degrees C. Reduced flavin mononucleotide, but not reduced flavin adenine dinucleotide, served as an electron donor. The Km for trimethylamine oxide was 0.89 mM and Vmax was 1,450 U/mg of protein. The enzyme reduced chlorate with a Km of 2.2 mM and a Vmax of 350 U/mg of protein.

Direct electron transfer in immobilized flavoenzyme chemically modified graphite electrodes

Direct electron transfer between covalently immobilized flavoenzymes and a cyanuric chloride-modified graphite electrode is observed via differential pulse voltammetry. L-Amino acid oxidase and xanthine oxidase display peaks arising from the reduction of flavin adenine dinucleotide. Peak current enhancements are observed for both covalently attached enzymes compared to their free and adsorbed state voltammograms. Studies concerning flavin removal and reconstitution indicate that xanthine oxidase contains multiple flavin chromophores which are nonequivalent.

Dechlorination of DDT by membranes isolated from Escherichia coli.

The capacity of cellular components of Escherichia coli to metabolize DDT-14C was investigated. Washed membrane fractions were obtained by lysozyme treatment followed by osomotic shock. Gas chromatography with electron capture detection and thin-layer chromatography were used to measure the effect of exogenous Kreb’s cycle cofactors and intermediates on the metabolism of DDT by particulate components of the bacteria. Reductive dechlorination of DDT to TDE occurred in the membranous fraction of the bacterial cell and was stimulated by a factor (s) present in the cytoplasmic fraction. Isolated membranes produced substantial amounts of TDE only in the presence of exogenous flavin adenine dinucleotide (FAD), and the prior reduction of FAD is essential to the production of TDE. The presence of Kreb’s cycle energy inhibited TDE production, indicating that DDT does not accept electrons produced by the oxidation of Kreb’s cycle intermediates directly from the cytochrome system.

AMINO ACIDS AS SUBSTRATE FOR THE REDUCTION OF TELLURITE BY CELLS OF PROTEUS VULGARIS.

Potassium tellurite was reduced more rapidly inProteus vulgaris cells in the presence of glycine, lysine, methionine, ornithine, glutamic acid and leucine. Reduction was probably bound to the activity of L-amino acid oxidases. Tellurite probably acted as an acceptor of hydrogen from reduced flavin adenine dinucleotide (FAD). Nicotine amide dinucleotide (NAD) also significantly stimulated reduction. Reduction was sensitive to SH-group inhibitors and party to KCN. Oxygen competed with the tellurite. The optimum pH was 6.7 and 7.3. Reduction did not take place in cells whose inner structure was injured.