Design of PG-Surfactants Bearing Polyacrylamide Polymer Chain to Solubilize Membrane Proteins in a Surfactant-Free Buffer

Abstract

The development of techniques capable of using membrane proteins in a surfactant-free aqueous buffer is an attractive research area, and it should be elucidated for various membrane protein studies. To this end, we examined a method using new solubilization surfactants that do not detach from membrane protein surfaces once bound. The designed solubilization surfactants, DKDKC12K-PAn (n = 5, 7, and 18), consist of two parts: one is the lipopeptide-based solubilization surfactant part, DKDKC12K, fand the other is the covalently connected linear polyacrylamide (PA) chain with different Mw values of 5, 7, or 18 kDa. Intermolecular interactions between the PA chains in DKDKC12K-PAn concentrated on the surfaces of membrane proteins via amphiphilic binding of the DKDKC12K part to the integral membrane domain was observed. Therefore, DKDKC12K-PAn (n = 5, 7, and 18) could maintain a bound state even after removal of the unbound by ultrafiltration or gel-filtration chromatography. We used photosystem I (PSI) from Thermosynecoccus vulcanus as a representative to assess the impacts of new surfactants on the solubilized membrane protein structure and functions. Based on the maintenance of unique photophysical properties of PSI, we evaluated the ability of DKDKC12K-PAn (n = 5, 7, and 18) as a new solubilization surfactant.

Research progress of photo-crosslink hydrogels in ophthalmology: A comprehensive review focus on the applications

“…Polyacrylamide (PAM) is a neutral polymer formed by copolymerization of acrylamide homopolymer or other monomers. As a linear polymer, PAM displays good thermal stability [ 107 ]. Moreover, the abundance of amide groups in the structural unit of polypropylene diluted amide facilitates the formation of hydrogen bonding, resulting in excellent water solubility and chemical activity, consequently, it finds extensive applications in the medical and various other industries [ 105 ].…”