Rational Design of a Cu(II) Spin Label Improves the Sensitivity of Distance Measurements.

ABSTRACT: The measurement of distance constraints in biomolecules using Cu(II) spin labels at Q-band EPR is complicated due to the selective excitation of only some orientations of the label. Here, we introduce a new Cu(II) spin label, in which the divalent metal is coordinated equatorially by four nitrogen atoms. Such chelation reduces the g anisotropy of the Cu(II) spin, which reduces the spectral width. We show that the complex coordinates to target labeling sites on a protein and provides narrow distance distributions on proteins. DEER data acquired across different fields at Q-band show the same period of modulation, which suggests proper orientational averaging. Thus, a single measurement at the magnetic field corresponding to the maximum intensity is sufficient to measure the distance

SUBMITTER: Palit S 

PROVIDER: S-EPMC12498500 | biostudies-literature | 2025 Oct

REPOSITORIES: biostudies-literature