Excellence in Research: Evaluating thiol-peptides with auxiliary binding groups as chelators of mercury(II)

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In this project, co-funded by the Historically Black Colleges and Universities Undergraduate program and the Chemical Structure, Dynamic and Mechanism B program, Professor Maria Ngu-Schwemlein and her collaborator Dr. John Merle, of the Chemistry Department at Winston Salem State University are developing eco-friendly biomolecules to sequester toxic mercury ions. The goal of this project is to design effective thiol-peptides to immobilize mercury ions for applications in environmental remediation of mercury polluted water, and as sensors or reporters of mercury ions. It may also afford a basis for future research in developing genetically engineered plants that are useful for phytoremediation. This project lies at the interface of bioorganic, inorganic, analytical, and computational chemistry, and therefore provides an excellent breadth of education for scientists and students. The project activities also provide a high level of education and research training to prepare undergraduates, primarily underrepresented groups at this historically black university, for entry into advanced degree programs and careers in science. Peptides offer inherent high affinities for their targets due to the versatility of its monomeric units, which offer a wide variety of donor atoms and contribute to specific secondary structures. The proposed syntheses include thiol-peptides with different auxiliary binding groups to evaluate complex formation with mercury(II) and to assess for enhanced mercury(II) immobilization through increased complex stability. In this project, oligopeptides consisting of di- or multi-cysteinyl residues with added auxiliary groups (O-, N-, or aromatic pi donors) are prepared to answer the following questions: (1) How do multi-thiol peptides containing different auxiliary donors form complexes with mercury(II)? (2) Can auxiliary binding groups form significant binding specificities resulting in sterically hindered peptide-mercury complexes that are kinetically stable? (3) What is the significance and stability of type II beta turn in cysteinyl peptides for binding mercury(II)? (4) What are the spatial accessibilities in these peptide ligands that can be identified for chemical conjugation with carriers or fluorophores for immobilizing and sensing mercury(II)? The findings from this study could be useful for developing effective chelators of mercury(II) for applications in environmental remediation, human health protection, and sensing.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.