title: Deconvolution of complex differential scanning calorimetry profiles for protein transitions under kinetic control.
abstract: A frequent outcome in differential scanning calorimetry (DSC) experiments carried out with large proteins is the irreversibility of the observed endothermic effects. In these cases, DSC profiles are analyzed according to methods developed for temperature-induced denaturation transitions occurring under kinetic control. In the one-step irreversible model (native → denatured) the characteristics of the observed single-peaked endotherm depend on the denaturation enthalpy and the temperature dependence of the reaction rate constant, k. Several procedures have been devised to obtain the parameters that determine the variation of k with temperature. Here, we have elaborated on one of these procedures in order to analyze more complex DSC profiles. Synthetic data for a heat capacity curve were generated according to a model with two sequential reactions; the temperature dependence of each of the two rate constants involved was determined, according to the Eyring's equation, by two fixed parameters. It was then shown that our deconvolution procedure, by making use of heat capacity data alone, permits to extract the parameter values that were initially used. Finally, experimental DSC traces showing two and three maxima were analyzed and reproduced with relative success according to two- and four-step sequential models.
authors.affiliation: Área de Biofisicoquímica, Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, Iztapalapa, D.F. 09340, Mexico.
authors.forename: Citlali
authors.initials: C
authors.lastname: Toledo-Núñez
authors.affiliation: Área de Biofisicoquímica, Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, Iztapalapa, D.F. 09340, Mexico.
authors.forename: L Iraís
authors.initials: LI
authors.lastname: Vera-Robles
authors.affiliation: Departamento de Procesos y Tecnología, Universidad Autónoma Metropolitana-Cuajimalpa, Cuajimalpa, D.F. 05300, Mexico.
authors.forename: Izlia J
authors.initials: IJ
authors.lastname: Arroyo-Maya
authors.affiliation: Área de Biofisicoquímica, Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, Iztapalapa, D.F. 09340, Mexico. Electronic address: aha@xanum.uam.mx.
authors.forename: Andrés
authors.initials: A
authors.lastname: Hernández-Arana
mesh_terms: D002152:Calorimetry, Differential Scanning / Q000379:methods; D008956:Models, Chemical; D011506:Proteins / Q000737:chemistry*
chemical_list: D011506:Proteins
keywords: Complex DSC profiles; Deconvolution; Differential scanning calorimetry; Kinetically controlled transitions; Rate constants