title: Conformational lock and dissociative thermal inactivation of lentil seedling amine oxidase.
abstract: The kinetics of thermal inactivation of copper-containing amine oxidase from lentil seedlings were studied in a 100 mM potassium phosphate buffer, pH 7, using putrescine as the substrate. The temperature range was between 47-60 degrees C. The thermal inactivation curves were not linear at 52 and 57 degrees C; three linear phases were shown. The first phase gave some information about the number of dimeric forms of the enzyme that were induced by the higher temperatures using the "conformational lock" pertaining theory to oligomeric enzyme. The "conformational lock" caused two additional dimeric forms of the enzyme when the temperature increased to 57 degrees C. The second and third phases were interpreted according to a dissociative thermal inactivation model. These phases showed that lentil amine oxidase was reversibly-dissociated before the irreversible thermal inactivation. Although lentil amine oxidase is not a thermostable enzyme, its dimeric structure can form "conformational lock," conferring a structural tolerance to the enzyme against heat stress.
authors.affiliation: Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran.
authors.forename: S Zahra
authors.initials: SZ
authors.lastname: Moosavi-Nejad
authors.forename: Ali-Akbar
authors.initials: AA
authors.lastname: Moosavi-Movahedi
authors.forename: Mostafa
authors.initials: M
authors.lastname: Rezaei-Tavirani
authors.forename: Giovanni
authors.initials: G
authors.lastname: Floris
authors.forename: Rosaria
authors.initials: R
authors.lastname: Medda
mesh_terms: D006631:Amine Oxidase (Copper-Containing) / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D019281:Dimerization; D004789:Enzyme Activation; D007700:Kinetics; D027806:Lens Plant / Q000201:enzymology*; D011487:Protein Conformation; D011489:Protein Denaturation; D036226:Seedlings / Q000201:enzymology; D013696:Temperature; D013816:Thermodynamics
chemical_list: D006631:Amine Oxidase (Copper-Containing)