Sigmatropic rearrangement enables access to a highly stable spirocyclic nitroxide for protein spin labelling.

ABSTRACT: Spin labelling enables the study of biomolecules using electron paramagnetic resonance (EPR) spectroscopy. Here, we describe the synthesis of a cysteine-reactive spin label based on a spirocyclic pyrrolidinyl nitroxide containing an iodoacetamide moiety. The spin label was shown to be highly persistent under reducing conditions while maintaining excellent EPR relaxation parameters up to a temperature of 180 K. After successful double spin labelling of a calmodulin variant, interspin distances were measured by the EPR experiment double electron-electron resonance (DEER) at 120 K.

SUBMITTER: Sowinski MP 

PROVIDER: S-EPMC11973475 | biostudies-literature | 2025 May

REPOSITORIES: biostudies-literature