Addition of Oligoarginine to a Membrane Permeabilizing Peptide M-Lycotoxin Facilitates Intracellular Antibody...

Coacervate-based intracellular delivery of biomacromolecules has attracted our attention due to the feasibility of easy condensation of the biomacromolecules and their controllable release. Our laboratory has developed a unique, coacervate-based delivery system that uses the conjugate of the polysaccharide pullulan with membrane-permeabilizing peptides, including L17E and M-lycotoxin. This system enables immunoglobulin G (IgG) antibodies labeled with the negatively charged fluorophore Alexa Fluor 488 to enter the cytosol directly through the plasma membrane. Cyotosolic IgG distribution is complete within a few minutes after infusion initiation, and infusion can be achieved in serum-containing medium. The purpose of this study was to refine this system to reduce the amount of antibody required while maintaining satisfactory delivery efficiencies. Therefore, pullulan conjugates with M-lytocoxin bearing two to eight arginine residues were designed to enhance the interaction of M-lycotoxin with the cell membrane. The conjugates were able to form microcondensates with Alexa Fluor 488 labeled IgGs. The addition of arginine residues improved the efficiency of cytosolic infusion and successfully reduced the amounts of both antibodies and pullulan-peptide conjugates required for the delivery.