An electron spin-echo envelope modulation (ESEEM) study has been performed on the tyrosyl radical D· in photosystem II particles in the frequency region 8.6-9.3 GHz. The experimental data show the presence of at least one proton which is easily exchanged by deuterium. The isotropic aiso) and anisotropic (Tβ) hyperfine interactions of this proton are aiso=±4 MHz, Tβ=±9 MHz indicative of D· being a neutral tyrosyl radical. The ESEEM data of D· also exhibit a low-frequency modulation the amplitude and the frequency of which are strongly affected by the microwave frequency. Possible origins of this modulation are discussed.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry