X-BAND ESEEM SPECTROSCOPY OF N-15 SUBSTITUTED NATIVE AND INHIBITOR-BOUND SUPEROXIDE-DISMUTASE - HYPERFINE COUPLINGS WITH REMOTE NITROGEN OFHISTIDINE LIGANDS

The hyperfine couplings of the remote nitrogens of histidine ligands a re determined for the first time by an X-band ESEEM spectroscopy study of N-15-substituted superoxide dismutase (SOD). They show a significa nt difference between two groups of ligands with different orientation relative to the metal ion. The ESEEM spectra of N-15 SOD With cyanide as an inhibitor containing N-14 and N-15 are also discussed. They all ow some conclusions to be drawn about structural changes upon inhibito r binding and indicate the necessity of further multifrequency investi gations.