Organic probes for monitoring carbohydrate-lectin interactions

The research described herein used novel organic probes to examine carbohydrate-lectin interactions resulting in selective and specific biosensors. Two approaches are used to serve as a basis for constructing biosensors. The first system used sugar-substituted poly(p-phenyleneethynylene)s (PPEs) as a platform designed to bind selectively to a desired lectin. As the carbohydrates attached to the PPE interact with the lectins, a change in the optical properties of the polymer is observed signaling the presence of the targeted analyze. The assay is selective because only a certain lectin will bind the specific sugars attached to the PPE. The second system utilized Peptide-based Borono Lectins (PBLs) in which boronic acid moieties are covalently attached to a peptide backbone in order to bind selectively to sugars. Boronic acids are well established as efficient binders for carbohydrates in aqueous media. Defining a precise spatial orientation between two boronic acids is the most common method used to obtain selectivity for binding different saccharides. Complex carbohydrates and glycoproteins have been associated with the presence of numerous cancers and other infectious diseases. Here we illustrate that Peptide based Borono-Lectins (PBL)s can be used to develop selective sugar binders. The peptide not only serves as a backbone/support on which to mount the boronic acids, but the amino acid side-chains introduce additional diversity to aid in defining the sensor selectivity towards specific sugar containing molecules. The synthesis and screening of the PBL Library will be discussed along with the sequencing of the positive glycoprotein binders.