Margie Li
Harvard University
Discovery and Characterization of an Endosome Escape Enhancing Peptide
Efficient delivery of macromolecules into mammalian cells is the one of the major bottlenecks for protein therapy. We previously showed that superpositively charged proteins are efficiently endocytosed and can carry cargo protein across the cell membrane. However, most protein cargo did not reach the cytosol and were instead arrested in endosomes. Here, we designed and performed a screen to discover membrane-active peptides that could enhance endosomal escape of supercharged GFP (+36 GFP) fused proteins. From a screen of 36 peptides, one peptide showed consistent improvement for nuclear protein delivery. Further analysis and optimization clarified the requirements for peptide composition and conjugation. Research is ongoing to test the limits of applications for this endosome escape enhancing peptide.
Meredith Eno
Boston College
Utility of Allyl-Boron Nucleophiles in Palladium Catalyzed Cross-Coupling Reactions and their Application to the Total Synthesis of Bromophycolide F
Allyl-boron reagents have received much attention as nucleophilic cross-coupling partners in recent years due to their low toxicity, ease of preparation and functional group tolerance. In the past several years our group has used allyl- boron reagents extensively in the context of palladium-catalyzed allyl-allyl cross coupling, to obtain branched 1,5-dienes. The work to be presented will describe the development of a kinetic resolution to access optically enriched 1,5-enynes from racemic propargyl acetates through an allyl-propargyl cross coupling reaction. The use of allyl-boron nucleophiles in an intramolecular cross-coupling with C(sp2) electrophiles will also be presented, along with the application of this methodology to the total synthesis of Bromophycolide F.
Stavroula Hatzios, Ph.D.
Harvard Medical School and Brigham and Women's Hospital
Chemoproteomic discovery of serine proteases active during Vibrio cholerae infection
Activity-based protein profiling (ABPP) is a chemoproteomic tool for detecting active enzymes in complex biological systems. Small-molecule probes that are chemically tuned to react with a particular enzyme class allow selective detection, enrichment, and identification of active enzymes by mass spectrometry. ABPP can provide a more accurate assessment of enzymes that function under a particular set of conditions than either transcriptomic or non-activity based proteomic analyses since post-transcriptional and post-translational regulation can lead to an imperfect correlation between gene/protein expression and enzyme activity. We used ABPP to identify secreted serine hydrolases that are active during infection with Vibrio cholerae, the gram-negative bacterium that causes human cholera. By profiling serine hydrolase activity in the infant rabbit model of infection, we identified several bacterial and host enzymes that may mediate host-pathogen interactions and could be potential therapeutic targets. Four predicted serine proteases from V. cholerae were consistently active in infected rabbits and also in V. cholerae biofilms, surface-associated communities of bacteria that may facilitate bacterial survival during infection. We are currently characterizing the proteolytic substrates of these enzymes and their contribution to V. cholerae pathogenicity in order to better understand the enzymatic dialogue between this global enteric pathogen and the host.