EVIDENCE FOR A MAGIC MAGNETIC-CONFIGURATION BETWEEN FMN AND THE [2FE-2S](-CEPACIA() CENTER OF PHTHALATE DIOXYGENASE REDUCTASE OF PSEUDOMONAS)

The enzyme phthalate dioxygenase reductase of Pseudomonas cepacia cont ains two prosthetic groups, a flavin mononucleotide, and a [2Fe-2S] ce nter. Although these centers are separated by only 12 Angstrom accordi ng to the X-ray crystal structure, no magnetic coupling effects are de tected on their EPR spectrum in the NADH-reduced state of the enzyme i n which both centers are paramagnetic. In this paper, we demonstrate t hat the peculiar arrangement of the prosthetic groups together with th e location of the reducible iron site gives rise to a ''magic magnetic configuration'' for which the dipolar interactions cancel.