In this project funded by the Macromolecular, Supramolecular and Nanochemistry Program in the Chemistry Division, Professor Matthew B. Francis of the University of California, Berkeley, is synthesizing new materials for use in removing pollutants from water. The new materials are constructed by attaching proteins to polymer supports. Since proteins bind to highly toxic substances, the resulting hybrid materials can be used to remove pollutants such as PCBs, estrogens or other toxic organic chemicals from drinking water. In this project, procedures are being developed to more precisely control the ways that the protein and polymer are attached. Further studies are then carried out to determine how well the resulting materials bind to various pollutants that have proven difficult to remove from water. The work is having a broad impact on our ability to tackle difficult environmental problems by addressing challenges to public health, improving the safety of manufacturing processes, and helping to remedy environmental contamination sites. The work is having a further broad impact on the training of future scientists through a project that combines knowledge from multiple fields in chemistry, biology and materials science.
In this research, hybrid materials consisting of proteins attached to polymeric supports are being constructed. Proteins are unrivaled in their ability to bind highly toxic species in complex environmental samples. To use them for remediation purposes, new synthetic methods are needed to wed polypeptides with polymeric materials in such a way that the resultant substances can facilitate recovery and improve stability. In this project, new techniques to attach polymers and other supports to the N-terminal position of virtually any desired protein in a single, efficient chemical step are being developed. Two versatile chemical modifications are being studied. In both of these, a single instance of a desired functional group in a single location can be attached while producing stable linkages. The first strategy involves a chemoselective oxidative coupling reaction promoted by ferricyanide ion, while the second exploits the highly-selective reaction between pyridine-2-carboxaldehyde (P2CA) derivatives and N-terminal amino acids to form 4-imidazolidinones. Both strategies have already proven useful for the introduction of interesting functional groups on model proteins in good yields. This project is building on the earlier results by (1) developing new coupling agents and conditions to achieve increased levels of reactivity; (2) determining the effects of amino acid sequence on reactivity using combinatorial peptides libraries; and (3) confirming the observed reactivity patterns by attaching proteins and evolved peptoid ligands that can bind difficult-to-remove pollutants to inexpensive polymer supports. These new methodologies are being tested on PCBs, estrogens, and other toxic organic pollutants commonly found in drinking water sources. Heavy metal-binding versions of these agents are also being produced.