Heme-bound tyrosine vibrations in hemoglobin M: Resonance Raman, crystallography, and DFT calculation.

ABSTRACT: Hemoglobins M (Hbs M) are human hemoglobin variants in which either the α or β subunit contains a ferric heme in the α₂β₂ tetramer. Though the ferric subunit cannot bind O₂, it regulates O₂ affinity of its counterpart ferrous subunit. We have investigated resonance Raman spectra of two Hbs, M Iwate (α87His → tyrosine [Tyr]) and M Boston (α58His → Tyr), having tyrosine as a heme axial ligand at proximal and distal positions, respectively, that exhibit unassigned resonance Raman bands arising from ferric (not ferrous) hemes at 899 and 876 cm^-1. Our quantum chemical calculations using density functional theory on Fe-porphyrin models with p-cresol and/or 4-methylimidazole showed that the unassigned bands correspond to the breathing-like mo

SUBMITTER: Nagatomo S 

PROVIDER: S-EPMC9382339 | biostudies-literature | 2022 Jul

REPOSITORIES: biostudies-literature