Heme proteins paramagnetic

Reaction of nitric oxide with ferrohemoproteins produces paramagnetic NO-ligated heme proteins (S = 1/2, rhombic g tensors with principal values in the range 1.96-2.08). In many compounds studied so far by EPR the hf interaction of the NO nitrogen and of a second axial nitrogen is clearly resolved in the intermediate g-value region near... 

Mott transition, 25 170-172 paramagnetic states, 25 148-161, 165-169 continuum model, 25 159-161 ESR. studies, 25 152-157 multistate model, 25 159 optical spectra, 25 157-159 and solvated electrons, 25 138-142 quantitative theory, 25 138-142 spin-equilibria complexes, 32 2-3, see also specific complex four-coordinated d type, 32 2 implications, 32 43-44 excited states, 32 47-48 porphyrins and heme proteins, 32 48-49 electron transfer, 32 45-46 race-mization and isomerization, 32 44—45 substitution, 32 46 in solid state, 32 36-39 lifetime limits, 32 37-38 measured rates, 32 38-39 in solution, 32 22-36 static properties electronic spectra, 32 12-13 geometric structure, 32 6-11 magnetic susceptibility, 32 4-6 vibrational spectra, 32 13 summary and interpretation... 

Craven, P. A., and DeRubertis, F. R. (1978). Restoration of the responsiveness of purified guanylate cyclase to nitrosoguanidine, nitric oxide, and related activators by heme and heme proteins Evidence for the involvement of the paramagnetic nitrosyl-heme complex in enzyme activation. J. Biol. Chem. 253, 8433-8443. 

This section firstly includes discussion of the NMR properties of certain paramagnetic porphyrins and is then concerned with recent developments in the study of the heme proteins cytochrome c and myoglobin, both of which comprise single polypeptide chains to which a protoporphyrin IX is bound, and hemoglobin which consists of four subunit heme polypeptides. 

A development in the theory of nuclear relaxation in macromolecules by paramagnetic ions has been suggested by Gueron. (675) In the case of heme proteins there is a net polarization of the iron electronic spin magnetic moment which is oriented along the direction of the magnetic field. Modulation of this dipolar field due to the spin polarization (Curie spin) by rotational diffusion introduces an additional term into the expression for transverse relaxation [equation (18)] giving ... 

In order to complete the discussion of magnetic hyperfine interactions in paramagnetic heme proteins as detected by Mossbauer spectroscopy, reference should be made to the work of Champion et al. (58). There the influence of the halides F, Cl, and I on ferric chloroperoxidase was studied. The results presented in this work indicate that halide anions,... 

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