Protection of a Decapeptide from Proteolytic Cleavage by Lipidation and Self-Assembly into High-Axial-Ratio Microstructures:  A Kinetic and Structural Study

Abstract

We report on the synthesis, kinetics of proteolysis by trypsin, and morphological characterization of a novel lipidated decapeptide that spontaneously self-assembles in aqueous solutions into 0.5 μm diameter hollow tubules and helices that range in length from tens to hundreds of micrometers depending on formation conditions. We also report on an improved method for the tritioacetylation of peptides. Tight molecular packing of the peptide−amphiphile into a crystalline bilayer array forces tight packing between peptide headgroups, which was found to significantly protect the peptides from proteolysis by trypsin. Relief of this steric hindrance between peptide headgroups caused by solubilization of the bilayer into detergent micelles accelerated the rate of trypsin hydrolysis by 32,000-fold. Raman spectroscopy and circular dichroism spectropolarimetry were used to gain molecular-level insight into the difference between hydrolysis rates. Results obtained from these studies suggest that differences in molecular packing and conformation of the peptide headgroups in crystalline tubular and dispersed micellar phases determine the extent of proteolytic protection. Protection from proteolysis is considered a useful feature of lipidated peptide tubules for their potential use as a depot of bioactive peptides and other labile prodrugs at defined biological sites for sustained release.

Converting Peptides into Drug Leads by Lipidation

“…Compound 3 (Fig. 4a) formed hollow tubules or helical ribbons spontaneously; these self-assembled structures protected compound 3 from trypsin degradation [65]. Several reviews describing selfassembly mechanisms, compositions and applications of lipidated peptides were available [84,[101][102][103][104].…”

Peptide Amphiphile Micelles Self-Adjuvant Group A Streptococcal Vaccination

“…They have been shown capable of delivering biologically active peptides for a variety of applications including angiogenesis (19,20), osteogenesis (21,22), neurogenesis (23,24), atherosclerosis treatment (25), cancer therapy (26,27), and islet transplantation (28,29). Also, peptide amphiphile micelles are comprised of a high concentration of peptide (30), inhibit peptide degradation (31), and can greatly increase peptide intracellular delivery (32). Recent research by the Tirrell Group has shown that peptide amphiphile micelles that display a tumor-specific cytotoxic T cell epitope can function as a self-adjuvanting vaccine delivery system capable of inducing a tumor-suppressing immune response when given prophylactically (33).…”

Intermolecular Forces in the Self‐Assembly of Peptide Amphiphile Nanofibers

“…Synthetic materials that self-assemble with nanometer-scale features from polypeptides, [1][2][3] oligopeptides, [4][5][6] cyclic peptides, [7] and peptide amphiphiles [8][9][10] may contribute to regenerative medicine as scaffolds that mimic the complex architecture and biochemical functionality of native extracellular tissue. Our laboratory has previously reported on peptide amphiphile molecules (PAs) that self-assemble from aqueous media into three-dimensional networks of bioactive nanofibers.…”