title: A spectrophotometric method for determining the oxidative deamination of methylamine by the amine oxidases.
abstract: Previously published studies on the oxidative deamination of methylamine by the amine oxidases have determined the formation of radioactively labeled formaldehyde from [(14)C]methylamine. The present work describes a coupled spectrophotometric assay, using formaldehyde dehydrogenase, for the continuous determination of the oxidative deamination of methylamine by semicarbazide-sensitive amine oxidase (SSAO) and its potential use for determining methylamine concentrations in plasma. In this assay, the formaldehyde produced by methylamine deamination is further oxidized to formate, with the reduction of NAD(+), by formaldehyde dehydrogenase. The NADH generated is monitored continuously at 340 nm. Interference from the presence of a rotenone-insensitive NADH oxidase activity in crude tissue homogenates and microsomal fractions can be minimized by pretreating samples with Triton X-100 or substituting NAD(+) by APAD(+) in the coupled assay. This relatively inexpensive and reproducible assay procedure avoids the use of radioactively labeled material.
authors.affiliation: Departmento de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, 08193, Spain.
authors.forename: J M
authors.initials: JM
authors.lastname: Lizcano
authors.forename: M
authors.initials: M
authors.lastname: Unzeta
authors.forename: K F
authors.initials: KF
authors.lastname: Tipton
mesh_terms: D000445:Aldehyde Oxidoreductases / Q000378:metabolism*; D006631:Amine Oxidase (Copper-Containing) / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D001774:Blood Chemical Analysis / Q000379:methods*; D002417:Cattle; D006801:Humans; D007700:Kinetics; D008168:Lung / Q000378:metabolism; D008744:Methylamines / Q000097:blood / Q000378:metabolism*; D008956:Models, Chemical; D009243:NAD / Q000378:metabolism; D017830:Octoxynol / Q000494:pharmacology; D010100:Oxygen / Q000378:metabolism*; D016958:Pseudomonas putida / Q000201:enzymology; D015203:Reproducibility of Results; D012418:Ruminants; D012680:Sensitivity and Specificity; D013053:Spectrophotometry / Q000295:instrumentation* / Q000379:methods*; D013552:Swine; D013997:Time Factors
chemical_list: D008744:Methylamines; D009243:NAD; D017830:Octoxynol; C027451:methylamine; D000445:Aldehyde Oxidoreductases; C087006:formaldehyde dehydrogenase, glutathione-independent; D006631:Amine Oxidase (Copper-Containing); D010100:Oxygen