The effect of ligand field strength on nonresonance Raman characteristics of hemoproteins.
A series of hemoproteins were characterized using Raman spectroscopic technique under non-resonant (near-infrared excited) conditions. All the proteins used in this study contain an iron-protoporphyrin IX with a coordinated histidine as a proximal ligand. Hemoproteins exhibited a near-infrared Raman shift at 1372 cm-1, only when heme was in the ferric state, while the peak completely disappeared when heme iron was reduced. The intensity of this peak was weakened upon the coordination of electron-donating ligands to heme iron. Therefore, the characteristics of this peak are different from the oxidation marker band assigned by the resonance Raman spectroscopy, rather, the intensity is strongly related to the sixth ligand field strength. In addition, the peak intensity may also reflect the distance between heme iron and the sixth ligand.
Johjima
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Department of Forest Products, Kyushu University, Fukuoka, Japan.
Wariishi
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Tanaka
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H
D000818:Animals; D001665:Binding Sites; D002417:Cattle; D003574:Cytochrome c Group / Q000737:chemistry; D006420:Hemeproteins / Q000737:chemistry*; D006639:Histidine; D006735:Horseradish Peroxidase / Q000737:chemistry; D006736:Horses; D007501:Iron; D008024:Ligands; D008706:Methemoglobin / Q000737:chemistry; D008786:Metmyoglobin / Q000737:chemistry; D009206:Myocardium; D011524:Protoporphyrins; D013055:Spectrophotometry, Infrared; D013059:Spectrum Analysis, Raman / Q000379:methods
D003574:Cytochrome c Group; D006420:Hemeproteins; D008024:Ligands; D011524:Protoporphyrins; D008786:Metmyoglobin; D006639:Histidine; D008706:Methemoglobin; C028025:protoporphyrin IX; D007501:Iron; D006735:Horseradish Peroxidase