Structure of the Tyrosyl Biradical in Mouse R2 Ribonucleotide Reductase from High-Field PELDOR


  • We thank P. P. Schmidt for helping with the sample preparation and Prof. Lars Thelander (Umeå, Sweden) for supplying us with E. coli cells that overexpress mouse R2 protein. M.B. would like to acknowledge the Max Planck Society and the IRTG 1422 for financial support. PELDOR=pulse electron–electron double resonance.


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Paramagnetic centers rigidly embedded in proteins serve as a probe in structural studies of macromolecular complexes. Pulse EPR at high frequencies allows the determination of not only the distance but also the relative orientation of these centers (see tyrosyl radicals; C gray, O red, N blue). The method has considerable potential for studying the assembly of protein complexes.