title: Influence of quaternary structure on the state of the haem in carp and human methaemoglobins studied by resonance Raman scattering.
abstract: the resonance Raman spectra of carp and human methaemoglobin (metHb) derivatives in the T and R quaternary structures were measured in the frequency regions of 1200-1700 cm-1 and 100-600 cm-1. Conversion of carp and human fluoro metHb's to the T structure was accompanied by a frequency shift of the Raman line at 348 cm-1 to lower frequency by 5 cm-1, but all other lines were unaffected by the R-T transition. As the 348 cm-1 line was assigned to a porphyrin mode (v8) involving a bending motion of peripheral groups, the frequency change may be attributable to a change in van der Waals' interaction between haem and globin. On addition of inositol hexaphosphate to carp azide metHb, the intensity ratios of Raman lines (cm-1/cm-1), 1588/1567, 1641/1606, and 349/377, decreased. This indicates a shift of the high-spin/low-spin equilibrium towards high-spin side, in agreement with the rise in magnetic susceptibility. No distinct change was detected for the Raman spectra of aquo and cyano met Hb's on the R-T transition, even in the lower frequency region.
mesh_terms: D000818:Animals; D001386:Azides / Q000494:pharmacology; D002347:Carps / Q000097:blood*; D003486:Cyanides / Q000494:pharmacology; D003530:Cyprinidae / Q000097:blood*; D005459:Fluorides / Q000494:pharmacology; D006801:Humans; D008706:Methemoglobin / Q000032:analysis*; D011487:Protein Conformation; D013059:Spectrum Analysis, Raman; D014867:Water
chemical_list: D001386:Azides; D003486:Cyanides; D014867:Water; D008706:Methemoglobin; D005459:Fluorides