Light scattering characterization of synthetic MUC-1 peptides and their behavior in dilute solution

Human epithelial mucin, MUC-1 is frequently expressed in adenocarcinoma. The sequentially-repeating nature of the core protein 20 a.a. polypeptide chain on the surface of malignant cells makes it a potential target for immunotherapy. Addressing the physicochemical role of these peptide tandem repeats (VNTR) in the structure of MUC-1 we have been prompted to use dynamic light scattering as an experimental tool to investigate peptide polymer size and dynamics directly in solution. We synthesized oligomeric VNTR peptides (monomer, trimer and pentamer) and studied their free behavior in aqueous solution. Our results revealed the simultaneous presence of three different relaxation modes corresponding to three different sizes. The small size is related to the expected hydrodynamic radius of the individual peptides, whereas the large size is associated with the presence of higher order peptide aggregates. The appearance of a third mode in the monomeric and trimeric MUC-1 reveals an actual peptide interaction.