Question

1. Within 10 amino acids, only two types of amino acids are used to make peptides, and micelles are prepared using these.
2. Considering the properties of the hydrophobic anti-cancer agent and siRNA, the hydrophobic anti-cancer agent is designed to be encapsulated inside the micelle and the siRNA is designed to bind to the micelle surface.

Design a peptide that satisfies the above two conditions.

Answer 1

Micelles are amphiphiles composed of a hydrophobic tail and a hydrophilic head. For this particular anti-cancer agent delivery system, amphiphilic peptides can be synthesized that usually consists of two parts: a hydrophobic tail composed of several hydrophobic amino acids and a hydrophilic head composed of one or two hydrophilic amino acids.

For example, the hydrophobic tail could be designed by employing different hydrophobic amino acids including Gly, Ala, Val, Leu, and Ile. The hydrophilic head could be designed by using positively charged Lys, His and Arg; or negatively charged Asp and Glu; generating cationic or anionic surfactant-like peptides, respectively.

Since siRNA is negatively charged, the hydrophilic head should be designed using positively charged Lys, His and Arg.

Example peptide: Gly-Ala-Val-Leu-Ala-Val-Lys-Arg