First, hydrogen bonding is a driving force of synthesis in PNTs. Glutamine is used in the structure because it is a polar amino acid, having hydrogen-bonding donor/ acceptor capability in its amide side chains. Therefore, it can contribute in the formation of PNTs. Second, PNTs are synthesized assuming the hypothesis that hydrophobic interac- tions play the dominant part in the orientation of nanotubes. The hydrophobic character is important because PNTs are formed in aqueous solution. If amino acid residues are to have no interaction with water molecules, hydrogen bonding between the peptide subunit is strengthened, making formation of the PNTs easier.