Allowance for thermodynamic nonideality in the characterization of protein interactions by spectral techniques

作者：Wills Peter R; Winzor Donald J^*

来源：Biophysical Chemistry, 2011, 158(1): 21-25.

DOI：10.1016/j.bpc.2011.04.011

• Difference spectroscopy
• Fluorescence quenching
• Molecular crowding
• Protein-protein interactions
• Thermodynamic nonideality

Theory is developed for the characterization of protein interactions by spectral techniques, where the constraints of constant temperature and pressure demand that thermodynamic activity be defined on the molal concentration scale. The customary practice of defining the equilibrium constant (K) on a molar basis is accommodated by developing expressions to convert those experimental values (K(molar)) to their thermodynamically more rigorous counterparts (K(molal)). Such procedures are illustrated by reanalysis of published results for the effects of molecular crowding agents on the isomerisation of alpha-chymotrypsin and reversible complex formation between catalase and superoxide dismutase. Although those reanalyses have led to only minor refinements of the quantitative interpretation, it is clearly preferable to adopt thermodynamic rigor throughout future spectral studies by employing the molal concentration scale from the outset.

• 出版日期2011-9