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2014 (published: 11.09.2014)
Number 3(21)
Home > Issue > Effect of the metal-ligand interaction in the heme group
on the colour of myoglobin forms
Murashev S.V., Bolshakova O.S.
In complex heterogeneous molecules consisting of organic part with ions of metal, the color may depend on both components. For this, both parts of the molecule are to be optically active in the visible part of the spectrum. Transition metal ions are optically active in the visible region, which are represented by iron ions, as a part of heme of myoglobin. For the color to exist, the organic part of a complex molecule contains a system of conjugated double bonds of certain extent. The color of a whole molecule should represent a superposition of colors of both components of a complex molecule. The colour shift in case of transformation of one myoglobin form to another is regarded in terms of metal-ligand interaction in the pigment heme group. Iron ion in the myoglobin heme group of one of the six coordinate bonds can interact with ligands which have various polarizabilities. Besides, the iron ion charge changes according to the myoglobin form, which affects the interaction with ligands includingthe electron density distribution. That is why the iron ion charge and its ability to get bound with various ligands cause the colour shift of myoglobin forms.
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Keywords: methmyoglobin, myoglobin, oxymyoglobin, iron ion, ligands and their polirazability, colour of myoglobin forms.
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License
UDC 644-4
Effect of the metal-ligand interaction in the heme group
on the colour of myoglobin forms
In complex heterogeneous molecules consisting of organic part with ions of metal, the color may depend on both components. For this, both parts of the molecule are to be optically active in the visible part of the spectrum. Transition metal ions are optically active in the visible region, which are represented by iron ions, as a part of heme of myoglobin. For the color to exist, the organic part of a complex molecule contains a system of conjugated double bonds of certain extent. The color of a whole molecule should represent a superposition of colors of both components of a complex molecule. The colour shift in case of transformation of one myoglobin form to another is regarded in terms of metal-ligand interaction in the pigment heme group. Iron ion in the myoglobin heme group of one of the six coordinate bonds can interact with ligands which have various polarizabilities. Besides, the iron ion charge changes according to the myoglobin form, which affects the interaction with ligands includingthe electron density distribution. That is why the iron ion charge and its ability to get bound with various ligands cause the colour shift of myoglobin forms.
Read the full article
Keywords: methmyoglobin, myoglobin, oxymyoglobin, iron ion, ligands and their polirazability, colour of myoglobin forms.
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License