SCREENING DERIVATIZED PEPTIDE LIBRARIES FOR TIGHT-BINDING INHIBITORS TO CARBONIC-ANHYDRASE-II BY ELECTROSPRAY-IONIZATION MASS-SPECTROMETRY

This paper describes the use of electrospray ionization-mass spectrome try (ESI-MS) to screen two libraries of soluble compounds to search fo r tight binding inhibitors for carbonic anhydrase II (EC 4.2.1.1). The two libraries, H2NO2SC6H4C(O)NH-AA(1)-AA(2)-C(O)NHCH2CH2CO2H (1), whe re AA(1) and AA(2) are L-amino acids (library size: 289 compounds) or D-amino acids (256 compounds), were constructed by attaching tripeptid es to the carboxyl group of 4-carboxybenzenesulfonamide. Screening of both libraries yielded, as the tightest binding inhibitor, compound 1 (AA(1) = AA(2) = L-Leu; binding constant K-b = 1.4 X 10(8) M(-1)). The ability of ESI-MS to estimate simultaneously the relative binding aff inities of a protein to soluble ligands in a library, if general, shou ld be useful in drug development.