PULSED ULTRAFILTRATION MASS-SPECTROMETRY - A NEW METHOD FOR SCREENINGCOMBINATORIAL LIBRARIES

In response to the need for rapid screening of combinatorial libraries to identify new lead compounds during drug discovery, we have develop ed an on-line combination of ultrafiltration and electrospray mass spe ctrometry, called pulsed ultrafiltration mass spectrometry, which faci litates the identification of solution-phase ligands in library mixtur es that bind to solution-phase receptors. After ligands contained in a library mixture were bound to a macromolecular receptor, e.g., human serum albumin or calf intestine adenosine deaminase, the ligand-recept or complexes were purified by ultrafiltration and then dissociated usi ng methanol to elute the ligands into the electrospray mass spectromet er for detection. Ligands with dissociation constants in the micromola r to nanomolar range were successfully bound, released, and detected u sing this method, including warfarin, salicylate, furosemide, and thyr oxine binding to human serum albumin, and erythro-9-(2-hydroxy-3-nonyl )adenine binding to calf intestine adenosine deaminase. Repetitive bin d-and-release experiments demonstrated that the receptor could be reus ed, Thus, pulsed ultrafiltration mass spectrometry was shown to provid e a simple and powerful new method for the screening of combinatorial libraries in support of new drug discovery.