Investigating The Structural And Physiochemical Properties Of Collagen Mimetic Peptides With Modified Backbones

Samuel Douglas Melton, University of Pennsylvania

Abstract

Collagen is the most abundant protein found in mammalian systems and is critically important in a myriad of different regulatory pathways, prompting widespread effort to model and understand collagen-protein interactions. A network of hydrogen bonds, non-covalent interactions, sterics, and stereoelectronic effects hold collagen’s unique triple-helical quaternary structure together. The highly repetitive primary structure, generalized by a three amino acid triplet: (Xaa-Yaa-Glycine), is critical for this uncommon structural assembly.Our lab has been investigating how the incorporation of aza-glycine (azGly, azG) and aza- proline (azPro, azP) residues affect the triple-helical structure and thermal stability of collagen mimetic peptides (CMPs). Although we have previously shown azGly and azPro incorporation can affect the triple-helical thermal stability of CMPs, the model systems used were quite limited in scope. Herein, the impact of azGly and azPro incorporation on CMP stability and structure is demonstrated to be dependent on a variety of different factors. This was accomplished through the synthesis of peptide libraries containing these aza-amino acids, evaluation of CMP thermal stabilities along with refolding times, and by solving high-resolution crystallographic structures of triple-helical structures. Futhermore, we optimize the synthesis of azGly-containing CMPs, evaluate the binding of azGly-containing CMPs to a target protein, and investigate an alternative CMP model system. Collectively, this body of work reports the first comprehensive set of design guidelines for incorporating azGly and azPro residues into CMPs and sets the stage for the utilization and application of aza-collagen peptides within biologically relevant systems.