Part 1: Isolation of Orexin Receptor Regulators via a Microarray-Based,Two-Color Cell Binding Screen. Part II: Targeted Inactivation of Proteins triggered by Visible Light.
Part I. Isolation of orexin receptor regulators via a microarray-based, two-color, cell-binding screen. We have developed a novel two-color, cell-binding peptoid microarray screening approach with which we discovered new orexin receptor ligands. We found that peptoids on microarray, which showed preferential binding to receptor-expressing cells, indeed regulate the function of the receptor in living cells. Although cell-adhesion peptide microarrays have been used to isolate peptides that bind to cell surface receptors, this is the first time that a non-peptide, small molecule microarray has been used to do so. We also demonstrated that the pharmacophore of a hit peptoid can be rapidly identified through sarcosine scanning. Subsequent modifications of the pharmacophore yielded a potent antagonist (IC50 = 1.7 ? and an allosteric potentiator (EC50 = 120 nM) of the orexin receptor. Part II. Targeted Inactivation of Proteins Triggered by Visible Light Advances in genomics and proteomics have helped to provide thousands of potential drug targets and thus target validation strategies are more important than ever. Among target validation technologies, we are interested in chromophore-assisted light inactivation of proteins (CALI) since it allows for time-resolved protein knock-out in living cells. However, the practical use of this technology is limited, partially because of the low CALI efficiency of chromophores that are currently in use. To solve this problem, we developed a convenient system to compare different chromophores for their CALI efficiency, from which we found that Ru(II) complex is a photo-stable and unusually efficient CALI ?rhead?This finding led us to develop photo-chemical protein knock-out reagents?n which Ru(II) complex was conjugated to small molecule ligands targeting VEGFR2 or the 26S proteasome. When irradiated with visible light, these reagents showed significantly increased potencies in inhibiting VEGF-induced VEGFR2 activation or proteolytic activity of the 26S proteasome.