Abstract
Polyproline (PP) based polypeptides have broad applications as protein mimics, ordered materials, hydrogels, and surface coatings. However, a lack of rapid and efficient preparatory methods has challenged synthesis of well-defined high molecular weight materials. Here, we report facile and high-yielding methods for preparation and polymerization of Pro and trans-4-acetoxy-Pro N-carboxyanhdrides (NCAs). For decades, transition metal initiators of NCA polymerization were assumed to be nonstarters with Pro due to the lack of an amide NH proton. We carefully considered the known steps in the initiation mechanism and applied a Ni initiator that intercepts an intermediate and does not require an NH group. This initiator efficiently catalyzes controlled, living polymerization of Pro NCAs, revealing that routes alternate to the previously proposed mechanism must be at play. We also found Co species can catalyze Pro NCA polymerization, and we improved the synthetic methods to prepare the NCA monomers. Our methods are high-yielding and rapid and give tunable, end-functional PP-based homo, statistical, and block polypeptides. We characterized the conformation of PP and trans-4-hydroxy-PP by CD and confirmed the time scale for quantitative conversion from PPI to PPII helices. Overall, our data shed light on the general propagation mechanism of transition metal catalyzed NCA polymerization and have opened the door for efficient preparation of a desirable class of biomaterials.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.