Demonstration of selectivity. CAV(1-104) and several control proteins were labeled with rhodamine and screened against duplicate SPOT sheets containing ligands 5, 6, and 1 to demonstrate selectivity of the ligand. Bovine serum albumin (BSA), casein, and hen egg white lysozyme (HEWL) all bound ligand 1 with reduced apparent affinity relative to CAV(1-104) as measured by fluorescence. Blank SPOTs containing only the double β-Ala linker were included as negative controls, and these baseline signals were subtracted from the corresponding signal for ligands 5, 6 and 1 SPOTs on each sheet.