(190ag) Functionalized Calixarene Based Surfaces for Highly Selective Protein Capture

Dialysis related amyloidosis (DRA) is a significant disease associated with patients with chronic renal failure. Current hemodialysis techniques are unable to remove β2microglobulin (β2m) from the blood of dialysis patients, resulting in β2m aggregates and protein deposits in their joints that may lead to carpal tunnel syndrome, spondyloarthropathies, hemarthrosis, joint pain and immobility. We thereby propose the development of functionalized calixarene based surfaces that target specific areas, like charged amino acid clusters and cavities on the surface of proteins to enhance selective protein capture, using molecular dynamics (MD) simulations. Such surfaces can also find applications in pharmaceutical manufacturing, biosensor technology, medicine and immobilized enzyme technology

The molecular-level understanding of protein interactions with calixarene-functionalized surfaces is currently very limited. We therefore use MD as a cost effective way to determine optimal functionality, surface grafting strategy for calixarenes. We have modeled diverse calixarenes with functional groups targeting charged, polar uncharged and hydrophobic patches on β2m, lysozyme and cytochrome C. We rank these affinities in terms of Gibbs free energy using protein – ligand docking simulations. We confirm the predictions of docking simulations by performing all atom simulations of proteins with free functionalized calixarenes. Finally, we predict the selectivity of calixarene based surfaces from the results of the above simulations.

The interactions of the carboxylic acid groups on calixarenes with the ε-amino groups of lysine residues of cytochrome C have been previously demonstrated experimentally by others to be responsible for functionalized calixarene selectivity between cytochrome C and lysozyme. The electrostatic potential maps of the cytochrome C and lysozyme from our investigations have provided different charged amino acid clusters on these proteins, which otherwise have similar molecular weights and isoelectric points. We demonstrate that functionalized calixarenes provide a unique architecture for protein recognition and capture. Their central cavity provides for an extended contact with large target molecules, such as proteins. Their upper or lower rims can be functionalized to maximize the interactions with target molecules.