Small Hydrophobic peptides Demonstrate Periodicity in Pampa

In an effort to find an ideal length for small linear peptide drugs we discovered a length-dependent periodicity in permeability as determined by the parallel artificial membrane permeability assay (PAMPA). This modern high-throughput assay is quickly becoming a preliminary step in estimating oral bioavailability of new compounds and thus their potentials as drug leads. Assaying peptides in this was has previously been problematic because of peptides lack of useful chromophore and low extinction coefficient at useful wavelengths. To circumvent this we used to fluorescent molecules, coumarin and dansyl, to quantitatively measure concentrations of peptides in phosphate buffer saline. Molecular modeling along with testing different hydrophobic side chains altering steroechemistry and testing different fluorophores will help elucidate the source of this periodicity.