A new azobenzene-based design strategy for detergents in membrane protein research.

Leonhard H Urner,Idlir Liko,Kristin Folmert,Christian Manz,Yasmine B Maier,Maiko Schulze,Carol V Robinson,Rainer Haag,Stephan Warnke,Waldemar Hoffmann,Kevin Pagel

doi:10.1039/d0sc01022g

Abstract

Mass spectrometry enables the in-depth structural elucidation of membrane protein complexes, which is of great interest in structural biology and drug discovery. Recent breakthroughs in this field revealed the need for design rules that allow fine-tuning the properties of detergents in solution and gas phase. Desirable features include protein charge reduction, because it helps to preserve native features of protein complexes during transfer from solution into the vacuum of a mass spectrometer. Addressing this challenge, we here present the first systematic gas-phase study of azobenzene detergents. The utility of gas-phase techniques for monitoring light-driven changes of isomer ratios and molecular properties are investigated in detail. This leads to the first azobenzene detergent that enables the native mass spectrometry analysis of membrane proteins and whose charge-reducing properties can be tuned by irradiation with light. More broadly, the presented work outlines new avenues for the high-throughput characterization of supramolecular systems and opens a new design strategy for detergents in membrane protein research.

Highlights

Proteins are molecular machines that are vital for living organisms
Our data underline that IM-MS allows us to analyse in addition how the overall shape of azobenzene detergents is affected by the interplay between (i) isomeric state, (ii) general molecular architecture, and (iii) size and exibility of the hydrophobic backbone; all of which determine the aggregation behaviour of azobenzene detergents.[23,24,27,42]
The ability to quantify isomer ratios of azobenzene detergents in solution by IM-MS depends on instrument conditions and ion properties

Summary

Introduction

Proteins are molecular machines that are vital for living organisms. Approximately 30% of the proteome is associated with membranes. We explore the utility of gas-phase techniques for quantifying their relative cis/trans ratios from solution and analyse how the molecular shape of these detergents is affected by (i) their isomeric state, (ii) general architecture, and (iii) structure of the hydrophobic backbone.

Results

Conclusion