Picomole-scale characterization of protein stability and function by quantitative cysteine reactivity

Department of Biochemistry, Duke University, DUMC Box 3711, Durham, NC 27710, USA.
Proceedings of the National Academy of Sciences (Impact Factor: 9.67). 03/2010; 107(11):4908-13. DOI: 10.1073/pnas.0910421107
Source: PubMed


The Gibbs free energy difference between native and unfolded states ("stability") is one of the fundamental characteristics of a protein. By exploiting the thermodynamic linkage between ligand binding and stability, interactions of a protein with small molecules, nucleic acids, or other proteins can be detected and quantified. Determination of protein stability can therefore provide a universal monitor of biochemical function. Yet, the use of stability measurements as a functional probe is underutilized, because such experiments traditionally require large amounts of protein and special instrumentation. Here we present the quantitative cysteine reactivity (QCR) technique to determine protein stabilities rapidly and accurately using only picomole quantities of material and readily accessible laboratory equipment. We demonstrate that QCR-derived stabilities can be used to measure ligand binding over a wide range of ligand concentrations and affinities. We anticipate that this technique will have broad applications in high-throughput protein engineering experiments and functional genomics.

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Available from: Daniel G Isom
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    • "The analysis of fQCR unfolding curves has been described previously (Isom et al., 2010b, 2011b). The details of the pH-dependent fQCR experiment can be found in the Supplemental Experimental Procedures. "
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