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Active-sitve titration of pig plasma benzylamine oxidase with phenylhydrazine.

ABSTRACT: Pig plasma benzylamine oxidase is a protein containing cupric copper and pyridoxal phosphate. The pyridoxal phosphate is stably linked to the enzyme. Discrepancies in the numbers of active sites per molecule of enzyme are reported in the literature. This paper shows that the fully active pure enzyme contains 3 mol of pyridoxal phosphate per mol, whereas enzymes with a lower specific activity are shown by titration with phenylhydrazine to have a lower pyrdoxal phosphate content.

SUBMITTER: Buffoni F

PROVIDER: S-EPMC1165226 | biostudies-other | 1975 Feb

REPOSITORIES: biostudies-other

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A catalytic mechanism for the enzyme benzylamine oxidase from pig plasma.

Project description:Initial-velocity and product-inhibition studies on the enzyme benzylamine oxidase from pig plasma indicate that the order of substrate addition and product release is benzylamine on, ammonia off, oxygen on, hydrogen peroxide off, benzaldehyde off. Ammonia, but not benzaldehyde, is released under strictly anaerobic conditions which provides independent evidence for this order. Benzyl alcohol is a substrate for the enzyme. A chemical mechanism consistent with all the data is proposed.

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Properties of cupric ions in benzylamine oxidase from pig plasma as studied by magnetic-resonance and kinetic methods.

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The presence of an inhibitor of benzylamine oxidase in human blood plasma.

Project description:The presence of an inhibitor of benzylamine oxidase in human blood plasma was observed. It may be removed by use of either a DEAE-cellulose column or a Sephadex G-200 column.

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Methylamine and benzylamine induced hypophagia in mice: modulation by semicarbazide-sensitive benzylamine oxidase inhibitors and aODN towards Kv1.1 channels.

Project description:1. In starved mice, the anorectic activity of methylamine (MET) and benzylamine (BZ), both substrates of semicarbazide-sensitive benzylamine oxidases (Bz-SSAO), was compared with that of the potassium channel blocking agents charybdotoxin (ChTX), tetraethylammonium (TEA), gliquidone (GLI), ammonium chloride (NH(4)(+)) and of the anoressants amphetamine (AMPH) and nicotine (NIC). After i.c.v. administration, an approximate ranking order of potency was: ChTX> or =AMPH>NIC=TEA> or =GLI> or =MET>BZ>NH(4)(+). 2. Clorgyline (2.5 mg kg(-1) i.p.) or deprenyl (10 mg kg(-1) i.p.) potentiated the anorectic effect of i.c.v.-administered BZ, NIC and AMPH. The effect of TEA was increased only by deprenyl, while MET, NH(4)(+), ChTX and GLI were not affected by either of the inhibitors. 3. The Bz-SSAO inhibitors alpha-aminoguanidine (50 mg kg(-1) i.p.), B24 (100 mg kg(-1) i.p.) and MDL 72274 (2.5 mg kg(-1) i.p.) potentiated the effect of i.p., but not of i.c.v.-administered MET. 4. Antisense oligodeoxyribonucleotides (aODN) to Kv1.1 potassium channels abolished the effect of BZ and TEA, but was ineffective in reducing the activity of MET and other compounds. 5. These results suggest that MET is endowed with peculiar hypophagic effects at dosage levels that are not able to affect gross behaviour in mice. The effect of MET, differently from BZ, seems unrelated to an increase in the central release of monoaminergic mediators, as well as to a Kv1.1 blocking activity. Through a reduction of the endogenous breakdown of MET, Bz-SSAO inhibitors enhance the central pharmacological activity of this amine.

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Path Integral Calculation of the Hydrogen/Deuterium Kinetic Isotope Effect in Monoamine Oxidase A-Catalyzed Decomposition of Benzylamine.

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Development of an active site titration reagent for α-amylases.

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Isothermal titration calorimetry uncovers substrate promiscuity of bicupin oxalate oxidase from <i>Ceriporiopsis subvermispora</i>.

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