Premium
Heat‐induced denaturation and aggregation of ovalbumin at neutral pH described by irreversible first‐order kinetics
Author(s) -
Weijers Mireille,
Barneveld Peter A.,
Cohen Stuart Martien A.,
Visschers Ronald W.
Publication year - 2003
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.03242803
Subject(s) - kinetics , differential scanning calorimetry , ovalbumin , chemistry , activation energy , denaturation (fissile materials) , arrhenius equation , thermodynamics , reaction rate constant , arrhenius plot , order of reaction , analytical chemistry (journal) , chromatography , nuclear chemistry , physics , immune system , quantum mechanics , biology , immunology
The heat‐induced denaturation kinetics of two different sources of ovalbumin at pH 7 was studied by chromatography and differential scanning calorimetry. The kinetics was found to be independent of protein concentration and salt concentration, but was strongly dependent on temperature. For highly pure ovalbumin, the decrease in nondenatured native protein showed first‐order dependence. The activation energy obtained with different techniques varied between 430 and 490 kJ•mole −1 . First‐order behavior was studied in detail using differential scanning calorimetry. The calorimetric traces were irreversible and highly scan rate‐dependent. The shape of the thermograms as well as the scan rate dependence can be explained by assuming that the thermal denaturation takes place according to a simplified kinetic process where N is the native state, D is denatured (or another final state) and k a first‐order kinetic constant that changes with temperature, according to the Arrhenius equation. A kinetic model for the temperature‐induced denaturation and aggregation of ovalbumin is presented. Commercially obtained ovalbumin was found to contain an intermediate‐stable fraction (IS) of about 20% that was unable to form aggregates. The denaturation of this fraction did not satisfy first‐order kinetics.