Issue 35, 2022

Persistence length of α-helical poly-l-lysine

Abstract

The α-helix has a significant role in protein function and structure because of its rigidity. In this study, we investigate the persistence length, lp, of α-helical poly-L-lysine, PLL, for two molecular weights. PLL experiences a random coil–helix transition as the pH is raised from 7 to 12. Using light scattering experiments to determine the radius of gyration (Rg), hydrodynamic radius, (Rh), the shape factor (Rg/Rh), and second virial coefficient (A2), and circular dichroism to determine the helical content, we find the structure and lp of PLL as a function of pH (7.4–11.4) and ionic strength (100–166 mM). With increasing pH, we find an increase in lp from 2 nm to 15–21 nm because of α-helix formation. We performed dissipative particle dynamics (DPD) simulations and found a similar increase in lp. While this lp is less than that predicted by molecular dynamics simulations, it is consistent with other experimental results, which quantify the mechanics of α-helices. By determining the mechanics of helical polypeptides like PLL, we can further understand their implications to protein function.

Graphical abstract: Persistence length of α-helical poly-l-lysine

Supplementary files

Article information

Article type
Paper
Submitted
07 Jul 2022
Accepted
21 Aug 2022
First published
22 Aug 2022

Soft Matter, 2022,18, 6550-6560

Persistence length of α-helical poly-L-lysine

K. G. Wilcox, M. E. Dingle, A. Saha, M. J. A. Hore and S. Morozova, Soft Matter, 2022, 18, 6550 DOI: 10.1039/D2SM00921H

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