Design and development of an effective cell penetrating peptide carrier for successful mRNA delivery

However, recent research on specific amino acid substitutions in other peptides has shown a performance improvement; therefore, substitutions were made to RALA to establish RALA variants and to observe if they had a beneficial impact. With the RALA variants, one which demonstrated significant improvement was the RALA D variant, which involved substitutions of glutamic acid with aspartic acid, while the possibility of disulphide linkage was maintained.

Transfection in NCTC-929s improved by over 20% relative to RALA. Another variant, which showed improvement, included RALA KVIV 3, which suggested that hydrophobic amino acids clustered near the C-terminus improved performance. There was also RALA Isoleucine 2, implying that a β-methyl helix destabilising amino acid, positioned near a terminal end, may improve performance.