Open AccessThe Self‐Association of Chymotrypsinogen A
Author(s) -
Tung Ming Sung,
Steiner Robert Frank
Publication year - 1974
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1974.tb03456.x
Subject(s) - virial coefficient , limit (mathematics) , thermodynamics , association (psychology) , chemistry , sedimentation equilibrium , ionic strength , mathematics , statistics , chromatography , psychology , ultracentrifuge , mathematical analysis , physics , aqueous solution , psychotherapist
The self‐association of chymotrypsinogen A at pH 8.1 and at ionic strength of 0.021 has been examined by means of sedimentation equilibrium. The data have been analyzed by several methods and results compared. Application of the older methods available in the literature indicate that the concentration dependence of molecular weight may be well accounted for in terms of an indefinite association in which the consecutive stepwise association constants are equal and the second virial coefficient is small and positive. A new method has been developed, based on series expansion, which selects the values of the second virial coefficient and the set of statistically significant consecutive association constants which give the optimum least squares fit of the data. Application of this method indicates that the association extends at least to the tetramer. The best model for this process is that of a stepwise association for which the stepwise constants are of similar magnitudes and for which the upper limit of association is undefined. This is essentially equivalent to the indefinite model. Frontal analysis using gel filtration gives results compatible with the above model.