Site-specific tagging proteins via a rigid, stable and short thiolether tether for paramagnetic spectroscopic analysis.

Increasing the stability of protein bioconjugates and improving the resolution of protein complexes is important for spectroscopic analysis in structural biology. The reaction of phenylsulfonated pyridine derivatives and protein thiols generates a stable, rigid and short thiolether tether, which is valuable in high-resolution spectroscopic measurements.