Affinity Ranking in Compound Mixtures

Advances in chemical synthesis have enabled considerable sophistication in the construction of diverse compound libraries to probe protein function [61, 62). However, few general techniques exist that can directly assess binding mechanisms and evaluate ligand afEnities in a multiplexed format. To realize the full potential of combinatorial chemistry in the drug discovery process, generic and efficient tools must be applied that combine mixture-based techniques to characterize protein-ligand interactions with the strengths of diversity-oriented chemical synthesis. 

ACE50 experiment for a three-component mixture. Dashed lines indicate variation of that component s concentration by +3-fold (an overall 9-fold difference) highlighting that the method is insensitive to ligand concentration. See text for details. Reprinted from [39] with permission from the American Chemical Society. 

It is also noteworthy that the ACE50 technique for affinity ranking also allows mixture components to be classified as either allosteric or directly competitive with another ligand of interest. In the M2 example, reanalyzing the sigmoidal AGE50 curves in Pig. 3.13 as the ratio plots instead shows that the response ratios 

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