Mw. Polm et Tj. Schaafsma, TRIPLET-STATE MAGNETIC-RESONANCE AND FLUORESCENCE SPECTROSCOPY OF METAL-SUBSTITUTED HEMOGLOBINS, Biophysical journal, 72(1), 1997, pp. 373-382
Fluorescence detected magnetic resonance (FDMR) spectra detected at 59
6 nm of zinc-substituted hemoglobins at 4.2 K show a split D-E transit
ion, which is not observed for zinc protoporphyrins ligated by methyli
midazole in glasses. Incorporation of the zinc heme into the globin po
cket is also accompanied by a blue shift of the fluorescence of 20 nm
at 4.2 K. FDMR spectra recorded at 576 nm do not show the D-E splittin
g. The D-E splitting and the huge blue shift are not observed for the
magnesium-substituted hemoglobins. Fluorescence measurements at 4.2 K
and 77 K, and EPR measurements at 110 K, were carried out to obtain in
formation about the ligation states of the zinc and magnesium protopor
phyrins in glasses and in hemoglobin. The results are explained by con
sidering ligation effects and distortion of the porphyrin plane.