title: Mechanism of reaction of allylamine with the quinoprotein methylamine dehydrogenase.
abstract: Allylamine did not serve as an efficient substrate for methylamine dehydrogenase (EC 1.4.99.3) in a steady-state assay of activity and appeared to act as a competitive inhibitor of methylamine oxidation by methylamine dehydrogenase. Transient kinetic studies, however, revealed that allylamine rapidly reduced the tryptophan tryptophylquinone (TTQ) cofactor of methylamine dehydrogenase. The rate of TTQ reduction by allylamine was 322 s-1, slightly faster than the rate of reduction by methylamine. These data were explained by a kinetic mechanism in which allylamine and methylamine are alternative substrates for methylamine dehydrogenase. The apparent competitive inhibition by allylamine is due to a very slow rate of release of the aldehyde product, 0.28 s-1, relative to a rate of 18.6 s-1 for the release of the aldehyde product of methylamine oxidation. A reaction mechanism is proposed for the oxidative deamination of allylamine by methylamine dehydrogenase. This mechanism is discussed in relation to the reaction mechanisms of topa-bearing quinoprotein amine oxidases, the flavoprotein monoamine oxidase and the mammalian semicarbazide-sensitive amine oxidase.
authors.affiliation: Department of Biochemistry, University of Mississippi Medical Center, Jackson 39216-4505, USA.
authors.forename: V L
authors.initials: VL
authors.lastname: Davidson
authors.forename: M E
authors.initials: ME
authors.lastname: Graichen
authors.forename: L H
authors.initials: LH
authors.lastname: Jones
mesh_terms: D000499:Allylamine / Q000737:chemistry*; D001426:Bacterial Proteins / Q000737:chemistry; D045563:Indolequinones; D007700:Kinetics; D010084:Oxidation-Reduction; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000037:antagonists & inhibitors / Q000737:chemistry*; D010231:Paracoccus denitrificans / Q000201:enzymology; D011809:Quinones / Q000737:chemistry; D014364:Tryptophan / Q000031:analogs & derivatives / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D045563:Indolequinones; D011809:Quinones; C070569:tryptophan tryptophylquinone; D000499:Allylamine; D014364:Tryptophan; C021567:methylamine dehydrogenase; D000587:Oxidoreductases Acting on CH-NH Group Donors