Work

Compensating Effects of Urea and Trimethylamine-N-Oxide on the Heteroassociation of α-Chymotrypsin and Soybean Trypsin Inhibitor

Year: 2013

Type: article

Abstract: An assay for the determination of the equilibrium constant for heteroassociation of α-chymotrypsin and soybean trypsin inhibitor via fluorescence depolarization is described. Results obtained at neutral pH in saline buffer were consistent with prior determinations via sedimentation equilibrium and static light scattering. The dependence of the association equilibrium constant upon the concentrations of urea and trimethylamine-N-oxide (TMAO) added individually and in mixtures was determined at several temperatures. It was found that subdenaturing concentrations of urea decrease the extent of heteroassociation and that added TMAO increases the extent of heteroassociation. The effects of both cosolutes in mixtures upon the equilibrium heteroassociation of α-chymotrypsin and soybean trypsin inhibitor appear to be additive. A thermodynamic analysis of the combined results is presented.

Source: The Journal of Physical Chemistry B

DOI: 10.1021/jp4006923

Authors: Di Wu, Allen P. Minton

Institutions: National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases

Language: English

Topic: Protein Structure and Dynamics

Subfield: Molecular Biology

Field: Biochemistry, Genetics and Molecular Biology

Domain: Life Sciences

Open Access status: green

Funders: National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases

Award: Measurement of protein associations via static and dynamic light scattering