[Analysis of low temperature magnetic circular dichroism of high spin ferrihemoproteids in the near UV region].
Magnetic circular dichroism spectra of fluoride complexes of metmyoglobin, methemoglobin, and horseradish peroxidase in the region of 300-450 nm at temperatures from 300 to 2.1 K were measured and analyzed. The temperature dependence of magnetic circular dichroism in the Soret region was found to be different from that of other paramagnetic forms and from the theoretically predicted dependence. The difference is explained by the superposition of the pi-->pi*-transition of porphyrin with one (peroxidase) or two charge transfer transitions and by substantially different temperature dependences of magnetic circular dichroism for the transitions of the two types. By minimization of differences between the expected and observed temperature dependences of magnetic circular dichroism, the parameters of its temperature dependence for charge transfer transitions and the parameter D of the zero-field splitting of the electronic ground state of the heme were found. The values of D for the fluoride complexes of metmyoglobin (5.8 cm-1) and methemoglobin (6.1 cm-1) agree well with those obtained by other methods. The D value for the fluoride complex of horseradish peroxidase (8.8 cm-1) was determined for the first time.
Sharonov
Iu A
IuA
Engelgardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia.
D002942:Circular Dichroism; D005459:Fluorides / Q000737:chemistry*; D006735:Horseradish Peroxidase / Q000737:chemistry*; D008280:Magnetics; D008706:Methemoglobin / Q000737:chemistry*; D008786:Metmyoglobin / Q000737:chemistry*; D013696:Temperature
D008786:Metmyoglobin; D008706:Methemoglobin; D006735:Horseradish Peroxidase; D005459:Fluorides