title: Thermal inactivation, denaturation and aggregation of mitochondrial aspartate aminotransferase.
abstract: A comparative study of thermal denaturation and inactivation of aspartate aminotransferase from pig heart mitochondria (mAAT) has been carried out (10 mM Na phosphate buffer, pH 7.5). Analysis of the data on differential scanning calorimetry shows that thermal denaturation of mAAT follows the kinetics of irreversible reaction of the first order. The kinetics of thermal inactivation of mAAT follows the exponential law. It has been shown that the inactivation rate constant (k(in)) is higher than the denaturation rate constant (k(den)). The k(in)/k(den) ratio decreases from 28.8+/-0.1 to 1.30+/-0.09 as the temperature increases from 57.5 to 77 degrees C. The kinetic model explaining the discrepancy between the inactivation and denaturation rates has been proposed. The size of the protein aggregates formed at heating of mAAT at a constant rate (1 degrees C min(- 1)) has been characterized by dynamic light scattering.
authors.affiliation: Bach Institute of Biochemistry, Russian Academy of Sciences, Moscow, Russia.
authors.forename: Nikolay V
authors.initials: NV
authors.lastname: Golub
authors.forename: Kira A
authors.initials: KA
authors.lastname: Markossian
authors.forename: Natallia V
authors.initials: NV
authors.lastname: Kasilovich
authors.forename: Mikhail V
authors.initials: MV
authors.lastname: Sholukh
authors.forename: Victor N
authors.initials: VN
authors.lastname: Orlov
authors.forename: Boris I
authors.initials: BI
authors.lastname: Kurganov
mesh_terms: D000818:Animals; D024442:Aspartate Aminotransferase, Mitochondrial / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D008027:Light; D008929:Mitochondria, Heart / Q000201:enzymology; D011485:Protein Binding; D011489:Protein Denaturation; D012542:Scattering, Radiation; D013552:Swine; D013696:Temperature
chemical_list: D024442:Aspartate Aminotransferase, Mitochondrial