Quantitative Binding Affinity Measurement

The first measure of a candidate compound s efficacy in a drug discovery program is its specific binding affinity to a desired biomolecular target. Therefore, 

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Damborsky et al. (2015) used SPR for measuring real-time quantitative binding affinities and kinetics of the interactions of specific antibodies with different epitopes of free and complexed prostate-specific antigen (PSA) to be used in microfluidic immunoassay-based platforms for POC devices. The authors describe a selective, sensitive and reliable biosensor for prostate cancer diagnosis as a lab-on-chip device. 

The more active isomer (where activity refers to binding affinity at a defined receptor) is designated the eutomer, the less active is the distomer. The ratio of activities is the eudismic ratio, and its logarithm, the eudismic index, is then proportional to the difference in binding free energy between the enantiomers. The eudismic index is a quantitative measure of chiral discrimination. 

According to our experimental methods, NMR spectroscopy could detect compounds that bound to BACE, but did not provide a quantitative measure of the binding affinity, which, of... 

Robert, D, Amat, L. and Carb6-Dorca, R. (1999). Three-Dimensional Quantitative Structure-Activity Relationships from Timed Molecular Quantum Similarity Measures Prediction of the Corticosteroid-Binding Globulin Binding Affinity for a Steroid Family. J.Chem.Inf.Comput.Sci., 39, 333-344. [R]... 

The two quantities, catalytic proficiency (which has the dimensions in the example above) and rate enhancement (which is dimensionless in the example above), give a valid account of two aspects of enzyme catalysis. The catalytic proficiency, as the equilibrium constant for transition-state binding to the free enzyme, measures quantitatively the affinity of the free enzyme for the transition state. The free-energy equivalent of the catalytic proficiency gives the total transition-state stabilization by the enzyme. The rate enhancement, as the equilibrium constant for the expulsion of a substrate molecule from the active site of the enzyme and its replacement by a transition-state molecule, quantitatively describes the relative affinity of the enzyme for the transition state compared to the reactant-state substrate. 

Robert D, Amat L, Carbo-Dorca R. Three-dimensional quantitative structure-activity relationships from tuned molecular quantum similarity measures prediction of the corticosteroid-binding globulin binding affinity for a steroid family. J Chem Inf Comput Sci 1999 39 333-344. 

Consequently, in order to determine whether any of the combination of mutations did in fact include binding-site residues, the binding affinities of the mutated cohesins were also evaluated in a quantitative manner. The results are presented in Figure 1. In competitive enzyme-linked interaction assay, cELIA, the native cohesin was used as a standard to coat microtiter plates. The immobilized cohesin was then allowed to interact with an enzyme-linked dockerin solution together with a competitor cohesin (native or mutated) in the solution phase. The measured enzymatic activity, expressed as the percentage of activity detected in the absence of the soluble competitor, reflects die amount of dockerin bound to the immobilized cohesin standard. The IC50, i.e., the... 

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