Work

Specificity and reactivity of bromoacrylaldehyde spin labels

Year: 2025

Type: article

Abstract: Electron paramagnetic resonance (EPR) spectroscopy in combination with site-directed spin labelling provides information on structure and dynamics of biomolecules. Increasing the availability of spin labels with different properties is an elegant way to foster a more accurate analysis of the EPR data in relation to the biological problem investigated. In this study, we present a comparative investigation of labelling efficiency, surface accessibility, site specificity and width of the distance distributions obtained on two proteins with the nitroxide-based bromoacrylaldehyde spin label (BASL) versus the two commercial spin labels MTSL (methanethiosulfonate spin label) and MAP (maleimido proxyl). Based on the predicted distances from a rotamer library approach and on the experimental distance distributions, BASL is shown to provide generally narrower distance distributions compared to the other nitroxide labels. The exquisite surface specificity of BASL with respect to MAP could be successfully exploited to selectively label surface cysteines in proteins containing a high number of native cysteines. In addition, the distinct site-reactivity of BASL and MAP towards two surface-exposed cysteines was leveraged for orthogonal labelling strategies with nitroxide and gadolinium labels. • Demonstration of the selectivity towards surface-accessible proteins' side chains of a bromoacrylaldehyde spin label (BASL). • The specific reactivity towards surface sites was exploited for orthogonal labeling strategies. • Narrower monomodal distance distributions with BASL compared to two commercial nitroxides. • New BASL rotamer library available and implemented in MMM and DEERPREdict. • Advantages of rotamer analysis of protein ensembles from MD trajectories versus single structure predictions.

Source: Journal of Magnetic Resonance

DOI: 10.1016/j.jmr.2025.107953

Authors: Dominik Gendreizig, Christina Elsner, Svetlana Kucher, Gunnar Jeschke, Alistair J. Fielding, Enrica Bordignon

Institutions: University of Geneva, ETH Zurich, Institute of Molecular Physical Science, Liverpool John Moores University

Language: English

Topic: Electron Spin Resonance Studies

Subfield: Biophysics

Field: Biochemistry, Genetics and Molecular Biology

Domain: Life Sciences

Open Access status: hybrid

Estimated APC paid: $3,500

Funder: Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung