title: Differential scanning calorimetry of the effects of Ca2+ on the thermal unfolding of Pseudomonas cepacia lipase.
abstract: Thermal unfolding of P. cepacia lipase was observed by adiabatic differential scanning microcalorimetry in the absence and presence of calcium ions at pH 8, and thermodynamic parameters of unfolding were evaluated to analyze the unfolding mechanism of the enzyme. The temperature of unfolding was higher at higher concentrations of Ca2+. From the Ca2+ concentration-dependence of the unfolding temperature, the number of calcium ions that dissociated from the enzyme molecule upon unfolding was estimated to be one. These results confirmed the validity of the unfolding mechanism proposed previously: NCa2+ < = => D + Ca2+, where N and D represent the native and denatured states, respectively, of the enzyme.
authors.affiliation: Faculty of Bioresources, Mie University, Tsu, Mie 514-8507, Japan. akiyoshi@bio.mie-u.ac.jp
authors.forename: Akiyoshi
authors.initials: A
authors.lastname: Tanaka
authors.forename: Hayuki
authors.initials: H
authors.lastname: Sugimoto
authors.forename: Yuko
authors.initials: Y
authors.lastname: Muta
authors.forename: Takafumi
authors.initials: T
authors.lastname: Mizuno
authors.forename: Keishi
authors.initials: K
authors.lastname: Senoo
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Obata
authors.forename: Kuniyo
authors.initials: K
authors.lastname: Inouye
mesh_terms: D016956:Burkholderia cepacia / Q000201:enzymology*; D002118:Calcium / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D005612:Freeze Drying; D006207:Half-Life; D006863:Hydrogen-Ion Concentration; D008049:Lipase / Q000737:chemistry*; D011489:Protein Denaturation; D017510:Protein Folding; D013696:Temperature
chemical_list: D008049:Lipase; D002118:Calcium