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Sterical Recognition at Helix–Helix Interface of Leu-Aib-Based Polypeptides with and without a GxxxG-Motif
- Itagaki, Toru, Uji, Hirotaka, Imai, Tomoya, Kimura, Shunsaku
- Langmuir 2019 v.35 no.22 pp. 7249-7254
- dimerization, ethanol, hydrophobicity, micelles, moieties, octoxynol, polypeptides, sarcosines, temperature
- An amphiphilic polypeptide, poly(sarcosine)-b-(l-Leu-Aib)₈ (SL16), was reported to self-assemble into vesicles. A GxxxG motif, which is known to induce helix dimerization, is incorporated into the hydrophobic helical block of SL16 to synthesize poly(sarcosine)-b-(l-Leu-Aib)₂-(Gly-Aib-l-Leu-Aib-Gly-Aib)-(l-Leu-Aib)₃ (SG16). SG16 shows helix association in ethanol at a high concentration and low temperatures, which is not observed with SL16. SG16 self-assembles into vesicles, but are found to be more susceptible to rupture by the addition of Triton X-100 than SL16 vesicles. A mixture of SL16 and SG16 self-assembles into small sheets and micelles likely because of mismatch of the modes of helix association arising from sterical accommodation of iso-butyl groups at the helix–helix interface.