Desorption/ionization on mesoporous silicate (DIOM)-mass spectrometry (MS) and ultrafiltration for target-based drug screening

This study presents a novel approach for rapid screening of combinatorial libraries to identify binding molecules for target proteins. Ultrafiltration coupled with desorption/ionization on mesoporous silicate (DIOM)-mass spectrometry (MS) provides a rapid, simple but powerful approach for the preliminary screening of active ligands toward specific target receptors. The feasibility of this strategy is demonstrated with a library of small molecule ligands (11 compounds) and the target protein, human serum albumin (HSA). Equimolar mixture of library was incubated with HSA under native binding conditions. Subsequently, the high molecular weight protein-drug complexes were selectively compartmented by ultrafiltration. The bound small molecular weight drugs were released and then recovered by denaturation of HSA for analysis by DIOM-MS directly provided clean mass spectra of binding compounds without any interference below 300 Da. This simple and robust method can preliminarily screen various chemical entities from a combinatorial mixture to find compounds with strong binding affinity (above 1.0 x 10(3) M-1) toward the target protein.