Dipolar interaction in multicenter proteins

FIGURE 11.2 Common cysteine binding pattern for two interacting cubanes. 

FIGURE 11.4 Fractional populations of half- and fully reduced pairs. The traces are for the idealized case of two S = 1/2 systems with identical EPR spectrum and identical reduction potential E° = 0.0 V. 

Another experiment to recognize interaction is based on its independence of the microwave frequency. If we increase the frequency, then the Zeeman interaction will gain relative importance, and the shape of the spectra should simplify. Experimentally, this may turn out to be a difficult approach due to the rapidly 

FIGURE 11.5 Half-held spectrum of two interacting cubanes. The signal from dihydropyrimidine dehydrogenase is of low intensity due to the relative weakness of the dipolar interaction. The g = 4.3 signal is a dirty iron contamination. 

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