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T Kido

Publications and source records attributed to T Kido.

At least 235 records · Page 13Linked to original sources
PubMed1978

Properties of 2-nitropropane dioxygenase of Hansenula mrakii. Formation and participation of superoxide.

2-Nitropropane dioxygenase, purified to homogeneity from a yeast, Hansenula mrakii, is significantly inhibited by superoxide dismutase and various scavengers for superoxide anion such as cytochrome c, epinephrine, NADH, thiols, and polyhydric phenols. The reduction of cytochrome c and the oxidation of epinephrine and NADH are concomitant with the inhibition of enzymatic oxygenation. Neither the oxidation nor the reduction occursin the presence of superoxide dismutase or in the absence of 2-nitropropane or oxygen. Superoxide anion added externally induces the oxygenation. These findings indicate the generation of superoxide anion and its participation in the oxygenation of 2-nitropropane. The difference spectrum of the binding of NADH to 2-nitropropane dioxygenase exhibits a negative peak at 353 nm. One mole of NADH is bound to 1 mol of the enzyme and the pro-R hydrogen of the nicotinamide moiety of bound NADH predominantly is transferred to superoxide anion formed enzymatically or given externally. Thus, the diastereotopic hydrogen of NADH is discriminated by the enzyme, although not completely.

Ascomycota↗
PubMed1978

Purification and properties of nitroalkane oxidase from Fusarium oxysporum.

A nitroalkane-oxidizing enzyme, which was inducibly formed by addition of nitroethane to the medium was purified to homogeneity from an extract of Fusarium oxysporum (IFO 5942) with an overall yield of about 20%. The enzyme catalyzed the oxidative denitrification of 1-nitropropane as follows: CH2(NO2)CH2CH3 + O2 + H2O leads to OHCCH2CH3 + HNO2 + H2O2. In addition to 1-nitropropane, 3-nitro-2-pentanol, 2-nitropropane, and nitrocyclohexane are good substrates; the enzyme is designated "nitroalkane oxidase" (EC class 1.7.3). The enzyme has a molecular weight of approximately 185,000 and consists of four subunits identical in molecular weight (47,000). Flavin adenine dinucleotide was required for the enzyme activity and could be replaced in part by riboflavin 5'-phosphate. The maximum reactivity was found at about pH 8.0. The enzyme was inhibited significantly by HgCl2, KCN, p-chloromercuribenzoate, and N-ethylmaleimide. The Michaelis constants are as follows: 1-nitropropane, 1.54 mM; 2-nitropropane, 7.40 mM; nitroethane, 1.00 mM; 3-nitro-2-pentanol, 3.08 mM; nitrocyclohexane, 0.90 mM; and flavin adenine dinucleotide, 1.33 micrometer.

Cyanates↗
PubMed1976

A new oxygenase, 2-nitropropane dioxygenase of Hansenula mrakii. Enzymologic and spectrophotometric properties.

2-Nitropropane dioxygenase, purified to homogeneity from Hansenula mrakii (IFO 0895), has a molecular weight of approximately 62,000 and consists of two subunits nonidentical in molecular weight (39,000 and 25,000). Stoichiometrical studies and the results obtained with 18O2 showed that 2 atoms of molecular oxygen are incorporated into 2 molecules of acetone formed from 2-nitropropane. In addition to 2-nitropropane, nitroethane, 3-nitro-2-pentanol, and 1-nitropropane are oxidatively dentrified. The enzyme, which exhibits absorption maxima at 274, 370, 415, and 440 nm and a shoulder at 470 nm, contains 1 mol of FAD and 1 g atom of non-heme iron per mol of enzyme. The enzyme-bound FAD is reduced by 2-nitropropane under anaerogic conditions, but the enzyme-bound Fe3+ is not affected. The introduction of oxygen to the reduced form of enzyme causes reoxidation of the enzyme. The bound FAD and Fe3+ are reduced by the addition of nitromethane, which is not a substrate, under anaerobic conditions. The aerobic dialysis of the enzyme treated with nitromethane causes reoxidation of only the Fe2+. Sodium dithionite also reduces both the enzyme-bound FAD and Fe3+ under anaerobic conditions. When the enzyme is dialyzed against 10 mM potassium phosphate buffer (pH 7.0) immediately after reduction by dithionite, the absorption spectrum similar to that of the native enzyme appeared with concomitant restoration of approximately 80% of the activity. The enzyme activity is significantly inhibited by pyrocatechol-3,5-disulfonate disodium salt, 8-hydroxyquinoline, reducing agents such as 2-mercaptoethanol, and HgCl2. The Michaelis constants are as follows: 2-nitropropane (2.13 X 10(-2) M), nitroethane (2.43 X 10(-2) M), 3-nitro-2-pentanol (6.8 X 10(-3) M), 1-nitropropane (2.56 X 10(-2) M), and oxygen (3.03 X 10(-4) M, with 2-nitropropane).

Amino Acids↗
PubMed1976

Purification and properties of nitroalkane-oxidizing enzyme from Hansenula mrakii.

A nitroalkane-oxidizing enzyme was purified about 1,300-fold from a cell extract of Hansenula mrakii grown in a medium containing nitroethane as the sole nitrogen source by ammonium sulfate fractionation, diethylaminoethyl-cellulose column chromatography, hydroxyapatite column chromatography, and Bio-Gel P-150 column chromatography. The enzyme was shown to be homogeneous upon acrylamide gel electrophoresis and ultracentrifugation. The enzyme exhibits absorption maxima at 274, 370, 415, and 440 nm and a shoulder at 470 nm. Balance studies showed that 2 mol of 2-nitropropane is converted into an equimolar amount of acetone and nitrite with the consumption of 1 mol of oxygen. Hydrogen peroxide is not formed in the enzyme reaction. In addition to 2-nitropropane, 1-nitropropane and nitroethane are oxidatively dentrified by the enzyme, but nitromethane is inert to the enzyme. The nitroalkanes are not oxidized under anaerobic conditions.

Acetone↗
PubMed1975

Microbial assimilation of alkyl nitro compounds and formation of nitrite.

66 representative strains of bacteria, yeasts and fungi were tested for their ability to grow in a semidefined medium containing 0.5% nitroethane as a nitrogen source. About half of them were found capable of growing in the medium. Hansenula beijerinckii, Candida utilis, and Penicillium chrysogenum were most active in assimilating nitroethane. 2-Nitropropane inhibited growth of most of the microorganisms tested in a medium containing 0.2% peptone and 0.2% glycerol. Hansenula mrakii was found to grow rapidly in the nitroethane-peptone medium after a lag phase. Nitrite was accumulated in the culture fluid after the phase of logarithmic multiplication, and increased with increase of the growth, followed by a decline after the maximum growth. The alkyl nitro compounds were oxidatively denitrified to form nitrite by the crude enzyme from Hansenula mrakii. Nitroethane was generally a poor substrate, but was the best inducer to produce the nitro compounds oxidizing enzyme. 2-Nitro-propane and nitroethane were enzymatically oxidized to nitrite, and acetone and acetaldehyde, respectively, which were isolated as 2,4-dinitrophenylhydrazones and identified. Nitrite formed was found to be reduced into ammonia by the intact cells and also the crude enzyme.

Acetaldehyde↗