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. Author manuscript; available in PMC: 2017 Jan 1.
Published in final edited form as: Wiley Interdiscip Rev Nanomed Nanobiotechnol. 2015 Jun 26;8(1):123–138. doi: 10.1002/wnan.1350

Figure 4. Peptide-based leucine zippers from GCN4 form nanoropes.

Figure 4

Nanorope formation is temperature and cosolute dependent. A) Phase image using tapping mode AFM of nanoropes formed in 1.5 M NaCl. The scale bar represents 500 nm and the z-scale represents 25 nm. B) Phase image of nanoropes formed in 0.75 M (NH4)2SO4 shows even longer structures than those in A). C,D) Circular dichroism was used to study the formation of alpha helices (-Θ222 nm for 144 μM peptide in 10 mM Tris, pH 8.0) as a function of C) cosolute concentration at 25 °C including Na2SO4 (●), (NH4) 2SO4 (▲), and NaCl (◆) and glycerol (inset graph) and D) temperature as a function of NaCl concentration, which shows that salt stabilizes the alpha helices until a higher temperature. Adapted with permission from PNAS49.