Ball, Zachary T2019-12-202021-05-012020-052019-12-19May 2020Mangubat-Medina, Alicia E. "Photocleavable approaches to reversible bioconjugation." (2019) Diss., Rice University. <a href="https://hdl.handle.net/1911/107957">https://hdl.handle.net/1911/107957</a>.https://hdl.handle.net/1911/107957The folding of peptides and proteins depends on the structural conformation of the amide backbone. Historically, side-chain modifications that respond to external stimuli, such as light, were a convenient technique for controlling folding and activity. As our curiosity into complex biological systems matures, so must the techniques used to probe these systems. While thoroughly less reported than light-sensitive side-chain modifications (called photocages), light-responsive modifications to the amide backbone structure represents a direct and powerful alternative to impact structural conformation. Using a copper-mediated, histidine-directed peptide backbone modification with vinyl boronic acids, it was possible to insert a traceless photocage into the N-H bond of the amide backbone. Several obstacles required addressing in order to achieve a traceless backbone photocage: first, the bond formed required a previously unreported photocleavage between C(sp2) and N atoms. Second, the photocaging reagents must maintain a minimum level of solubility in an aqueous solution. Finally, for maximized general use in biological systems, light-induce uncaging would ideally occur using visible light and near infrared light. Here, the first peptide backbone photocaging reagents are described. These represent a new class of photocaging reagents capable of tracelessly uncaging peptides using ultraviolet, blue, and near-IR light; reversibly disrupting peptide folding; reversibly interrupting enzymatic recognition of a peptide substrate; and reversibly modifying a model protein. These results represent a jumping point to developing a vast array of backbone photocages, optimized for a wide variety of contexts.application/pdfengCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.photocagephotocleavage2-photonpeptide backbonepeptide modificationprotein modificationcopper-mediatedhistidine-directedsite-specificreversiblelight sensitiveThesis2019-12-20