MetaCyc Enzyme: N-methylputrescine oxidase

Species: Hyoscyamus niger

Subunit composition of N-methylputrescine oxidase = [diamine oxidase]2

Molecular Weight of Polypeptide: 66 kD (experimental) [Hashimoto90]

Molecular Weight of Multimer: 135 kD (experimental) [Hashimoto90]

Gene-Reaction Schematic

Gene-Reaction Schematic

Enzymatic reaction of: N-methylputrescine oxidase

Inferred from experiment

N-methylputrescine + H2O + oxygen → N-methylaminobutanal + ammonium + hydrogen peroxide

The direction shown, i.e. which substrates are on the left and right sides, is in accordance with the direction in which it was curated.

The reaction is physiologically favored in the direction shown.

Alternative Substrates for N-methylputrescine: cadaverine [Hashimoto90], putrescine [Hashimoto90]

In Pathways: superpathway of hyoscyamine and scopolamine biosynthesis, N-methyl-Δ1-pyrrolinium cation biosynthesis

An N-methylputrescine oxidase has been partially purified from Hyoscyamus niger. The enzyme accepts N-methylputrescine, putrescine, and cadaverine as substrates, with N-methylputrescine being the best substrate. Inhibition of the enzyme activity by copper ligands and carbonyl reagents indicated that copper and pyrroloquinoline quinine are present at the active site of the enzyme.

Cofactors or Prosthetic Groups: pyrroloquinoline quinone [Hashimoto90], Cu2+ [Hashimoto90]

Inhibitors (Unknown Mechanism): Cu2+ [Hashimoto90], Hg2+ [Hashimoto90], p-chloromercuribenzenesulfonic acid [Hashimoto90], CdCl2 [Hashimoto90], potassium cyanide [Hashimoto90], N-methylpropylamine [Hashimoto90], N-methylbutylamine [Hashimoto90]Kinetic Parameters:
Substrate Km (μM) Citations
N-methylputrescine 330.0 [Hashimoto90]

pH(opt): 7.5-8 [Hashimoto90]


Hashimoto90: Hashimoto T, Mitani A, Yamada Y (1990). "Diamine Oxidase from Cultured Roots of Hyoscyamus niger: Its Function in Tropane Alkaloid Biosynthesis." Plant Physiol 93(1);216-221. PMID: 16667438

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Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
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