Colloid-like solution behavior of computationally designed coiled coil bundlemers

Nairiti J Sinha; Rui Guo; Rajkumar Misra; Jeffrey Fagan; Antonio Faraone; Christopher J Kloxin; Jeffery G Saven; Grethe V Jensen; Darrin J Pochan

doi:10.1016/j.jcis.2021.09.184

Colloid-like solution behavior of computationally designed coiled coil bundlemers

J Colloid Interface Sci. 2022 Jan 15;606(Pt 2):1974-1982. doi: 10.1016/j.jcis.2021.09.184. Epub 2021 Oct 1.

Authors

Nairiti J Sinha¹, Rui Guo², Rajkumar Misra³, Jeffrey Fagan⁴, Antonio Faraone⁴, Christopher J Kloxin⁵, Jeffery G Saven², Grethe V Jensen⁶, Darrin J Pochan⁷

Affiliations

¹ Department of Materials Science and Engineering, University of Delaware, Newark, DE, USA; NIST Center for Neutron Research (NCNR), National Institute of Standards & Technology (NIST), Gaithersburg, MD, USA.
² Department of Chemistry, University of Pennsylvania, Philadelphia, PA, USA.
³ Department of Materials Science and Engineering, University of Delaware, Newark, DE, USA.
⁴ NIST Center for Neutron Research (NCNR), National Institute of Standards & Technology (NIST), Gaithersburg, MD, USA.
⁵ Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, USA.
⁶ NIST Center for Neutron Research (NCNR), National Institute of Standards & Technology (NIST), Gaithersburg, MD, USA; Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, USA. Electronic address: gvj@teknologisk.dk.
⁷ Department of Materials Science and Engineering, University of Delaware, Newark, DE, USA. Electronic address: pochan@udel.edu.

PMID: 34749446
DOI: 10.1016/j.jcis.2021.09.184

Abstract

The use of isotropic potential models of simple colloids for describing complex protein-protein interactions is a topic of ongoing debate in the biophysical community. This contention stems from the unavailability of synthetic protein-like model particles that are amenable to systematic experimental characterization. In this article, we test the utility of colloidal theory to capture the solution structure, interactions and dynamics of novel globular protein-mimicking, computationally designed peptide assemblies called bundlemers that are programmable model systems at the intersection of colloids and proteins. Small-angle neutron scattering (SANS) measurements of semi-dilute bundlemer solutions in low and high ionic strength solution indicate that bundlemers interact locally via repulsive interactions that can be described by a screened repulsive potential. We also present neutron spin echo (NSE) spectroscopy results that show high-Q freely-diffusive dynamics of bundlemers. Importantly, formation of clusters due to short-range attractive, inter-bundlemer interactions is observed in SANS even at dilute bundlemer concentrations, which is indicative of the complexity of the bundlemer charged surface. The similarities and differences between bundlemers and simple colloidal as well as complex protein-protein interactions is discussed in detail.

Keywords: Bundlemer; Colloids; Computational design; Neutron spin echo (NSE); Protein–protein interactions; Small-angle neutron scattering (SANS).

MeSH terms

Colloids*
Diffusion
Peptides*
Proteins
Scattering, Small Angle

Substances

Colloids
Peptides
Proteins