Principal Investigator Brad Pentelute
The chemical modification of unprotected peptides and proteins has proved challenging because one-site often needs to be labeled or modified in the presence of many other functional groups. Consequently, the reactions employed need to be chemoselective, regioselective, and operational under mild, biomolecule “friendly” conditions. Fluorine-based molecules has played a major role in small molecule therapeutics - 30% of currently marketed small molecule drugs contain this element. We recently introduced a new technology which greatly expands the use of fluorine in peptides and proteins to favorably alter their properties. Specifically, we are developing an extensive toolkit for cysteine arylation of unprotected peptides and proteins based on SNAr "click" transformation between a thiolate and perfluoroaromatic species. As a further highlight of the chemistry and the significant consequence of installing the perfluoroaromatic linkers, we have rendered a bioactive peptide cell permeable and capable of selectively binding protein targets. We are currently developing a general platform based on this chemistry targeting inhibition of the p53/MDM2 interaction in cancer cells.
The regioselectivity, chemoselectivity, and high conversion efficiencies under exceedingly mild conditions have in part led us to propose an enzyme-catalyzed version of this reaction type. Initial experiments show that unprotected peptides can be ligated and probes may be conjugated to proteins under enzyme catalysis within minutes in water media. The unique feature of this enzyme catalyzed “click” ligation has allowed us to overcome a major challenge in bioconjugation for the site-specific labeling of one cysteine residue in the presence of another unprotected cysteine on the same polypeptide chain. We anticipate developing this chemistry for routine biomolecular modification and in parallel uncovering the added benefits for biological applications. Computational aspects of this work are done in a collaboration with the Lin laboratory at Tufts University.