Use of double spin-labeled histones to monitor histone-chromatin integration

Tyrosine-specific nitroxide spin labels have been synthesized that utilize either deuterium or deuterium and [15N] isotopic substitution within the nitroxide ring. These probes have been used to differentially spin label and simultaneously monitor both histones H1 and H5, during the displacement of endogenous spin-labeled H1 from reconstituted chromatin by exogenously added spin-labeled H5.