Intermolecular and intramolecular isotope effects in the deamination of putrescine catalyzed by diamine oxidase

Summary The enzymatic deamination of 1,4-diaminobutane (putrescine) catalyzed by hog kidney diamine oxidase was studied with the aid of deuterium labeled substrates and mass spectrometry. An intermolecular deuterium isotope effect for the deamination of putrescine labeled with deuterium in all 4 alpha positions was observed to be 1.26. 1,4-Diaminobutane-1, 1-d₂ was synthesized and intramolecular isotope effects determined. The preference of diamine oxidase for the unlabeled alpha position was about 4 times greater than for the deuterated methylene. This work shows that intramolecular deuterium isotope effects are observable in enzyme systems other than cytochrome P-450.Acknowledgment. This investigation was supported by a research grant from the National Institutes of Health, grant number NS 14017.     

Regioselectivity in the oxidative deamination of 2-methyl-1,4-diaminobutane catalyzed by diamine oxidases

Summary Diamine oxidase from pea seedlings (PDAO) catalyzes the oxidation of 2-methyl-1,4-diaminobutane in a regioselective fashion, whereas diamine oxidase from pig kidney (KDAO) shows no regioselectivity for the same reaction.This work was supported by Ministero della Pubblica Istruzione. We thank Prof. A. Fiecchi and Prof. S. Ronchi for many helpful discussions.     

Potentiation of histamine and inhibition of diamine oxidase by mescaline

Zusammenfassung Anhand zweier Versuchsanordnungen wird gezeigt, dass Meskalin Histaminwirkungen verstärken kann. Ausserdem vermag es die Histamin zerstörende Wirkung der Diaminooxydase zu hemmen (in 10^–5-molarer Konzentration).Es wird die Möglichkeit diskutiert, dass diese Eigenschaften mit der 4-Methoxyphenyl-äthylamin-Struktur des Meskalins in Zusammenhang stehen könnten.     

Effect of some monoamine oxidase inhibitors on deamination of biogenic monoamines by rat liver mitochondrial monoamine oxidase

N--N- MAO , , .     

Correlation betweenpara-phenylene diamine oxidase activity and the copper content of rat serum

Résumé Il y a une corrélation très forte entre l'activité de lapara-phénylène diamine oxydase du sérum sanguin du rat et de son taux en cuivre.     

Monoacylcadaverines as substrates for both monoamine oxidase and diamine oxidase; low rates of activity

Summary Monoacetylcadaverine and monopropionylcadaverine were found to be substrates for both rat liver monoamine oxidase and hog kidney diamine oxidase, but all the K_m-values for the oxidases were very high. The amines were common substrates for type A and type B monoamine oxidase.     

Effect of hepatocarcinogens on rat serumpara-phenylene diamine oxidase and xanthine dehydrogenase

Résumé On a observé une diminution de lapara-phénylène-diamine-oxydase et parfois une augmentation de la xanthine déhydrogenase dans le sérum sanguin des rats traités avec quelques substances cancérigènes pour le foie.     

Effect of phytic acid on diamine oxidase activity in germinating pea seeds

Summary Diamine oxidase present in the cotyledons of germinating pea seeds is induced by phytic acid but the embryo enzyme is not affected. Polyamines have no effect on phytase activity of the cotyledon or embryo.We thank Dr S. K. Srivastava for his helpful suggestions.     

Purification of pig kidney diamine oxidase (histaminase) and in vivo effects on passive cutaneous anaphylaxis and histamine induced bronchoconstriction of guinea-pigs

Summary Histaminase (diamine oxidase) was purified from pig kidney using cadaverine-Sepharose affinity chromatography. Pretreatment of guinea-pigs with histaminase caused marked inhibition of the passive cutaneous anaphylaxis. The effect of histaminase on histamine induced bronchoconstriction in vivo was studied. Histaminase significantly reduced the response in guinea-pigs. Histaminase is effective as a potent antihistaminic agent in vivo.     

Effect of phytic acid on diamine oxidase activity in germinating pea seeds.

Diamine oxidase present in the cotyledons of germinating pea seeds is induced by phytic acid but the embryo enzyme is not affected. Polyamines have no effect on phytase activity of the cotyledon or embryo.     

Deuterium isotope effects in the ninhydrin reaction of primary amines

Summary The rate of development of Ruhemann's purple in the ninhydrin reaction of two deuterated primary amines, -d₂-p-tyramine and -d₂--phenylethylamine, is significantly reduced It appears to be a primary isotope effect and indicates that the cleavage of the carbon-hydrogen bond at the -position is involved in the rate-determining step of the color reaction.Acknowledgements. We thank Dr A.A. Boulton for his advice and encouragement and the Canadian Medical Research Councel and Saskatchewan Health for their continuing financial support.     

Normalization by nucleotides of impairments in deamination of nitrogenous compounds in liver of tumor-bearing mice

-2 (3)--3- - .     

Monoamine oxidase inhibition by d-amphetamine in ganglia and nerve endings

Summary The inhibition of monoamine oxidase (MAO) activity by d-amphetamine was measured in homogenates of cat superior cervical ganglion and nictitating membrane, using tyramine (TM) and noradrenaline (NA) as substrates. In both tissues, d-amphetamine was shown to be a competitive inhibitor of the oxidation of TM. The Ki for d-amphetamine, as a MAO inhibitor, was lower in the ganglia than in the peripheral nerve endings.Supported by a Contract from the National Research Council of Argentina (CONICET) (Res. 67/79).     

Nitrite reduction by NADH, catalyzed by the nitrite reductase of Pseudomonas aeruginosa

Reduction of nitrite by NADH catalyzed by Pseudomonas aeruginosa nitrite reductase is inhibited by a high concentration of nitric oxide NO. Contrary to what is currently admitted, we find that the nitrite reduction proceeds to the nitrogen monoxide N2O stage. EPR spectra show that, during the catalytic cycle, the enzyme forms specific Fe2+-NO heminic complexes.     

Improving the thermal stability of lactate oxidase by directed evolution

Lactate oxidase is used in biosensors to measure the concentration of lactate in the blood and other body fluids. Increasing the thermostability of lactate oxidase can significantly prolong the lifetime of these biosensors. We have previously obtained a variant of lactate oxidase from Aerococcus viridans with two mutations (E160G/V198I) that is significantly more thermostable than the wild-type enzyme. Here we have attempted to further improve the thermostability of E160G/V198I lactate oxidase using directed evolution. We made a mutant lactate oxidase gene library by applying error-prone PCR and DNA shuffling, and screened for thermostable mutant lactate oxidase using a plate-based assay. After three rounds of screening we obtained a thermostable mutant lactate oxidase, which has six mutations (E160G/V198I/G36S/T103S/A232S/F277Y). The half-life of this lactate oxidase at 70 °C was about 2 times that of E160G/V198I and about 36 times that of the wild-type enzyme. The amino acid mutation process suggests that the combined neutral mutations are important in protein evolution. Received 15 September 2006; received after revision 21 October 2006; accepted 2 November 2006