Further Properties of Spermidine Dehydrogenase from Citrobacter freundii IFO 12681

Characterization of Membrane-bound Spermidine Dehydrogenase ofCitrobacter freundii

“…The measurement of enzyme activity, definition of enzyme activity, and measurement of protein content were done as described in our previous paper. 3) Amino acid composition. Analysis of amino acid composition was done with the purified enzyme (about 0.2/lmol).…”

“…A crystalline enzyme (0.2 mg, 180 units/mg) prepared from the soluble fraction 3 ) was mixed with the membrane fraction (10 mg) in the presence or absence of 3 M KCI in 10 ml of total volume. The membrane fractions used had been extensively washed with diluted buffer solutions or water until no appreciable amount of enzyme activity was observed in the supernatant.…”

“…Polyacrylamide gel electrophoresis, SDS-polyacrylamide gel electrophoresis (SDS-PAGE), analytical ultracentrifugation, and measurement of cytochrome were done under essentially the same conditions as described in our previous paper. 3) …”

“…The enzyme was found to be a single polypeptide including two prosthetic groups, heme b and a covalently bound carbonyl compound. 3 ) The carbonyl compound has been thought to be a covalently bound PQQ. The location of the enzyme in the organism is still unknown, though it catalyzes an important oxidative splitting reaction of spermidine into 1,3-diaminopropane and y-aminobutyraldehyde.…”

“…About a half of the total enzyme activity remains in the membrane fraction when separated the cell homogenate into the soluble fraction and membrane fraction. 3 ) Solubilization and further examinations of the membrane-bound spermidine dehydrogenase are essential in relation to the location of the enzyme. Thus, in this paper, the enzyme in the membrane fraction was solubilized and further purified to homogeneity.…”