Observations of elastic and quasi-elastic nuclear gamma resonance absorption in hemoglobin crystals

Abstract

Mössbauer spectra of carbonmonoxy-liganded human hemoglobin crystals, selectively enriched with 57Fe in the α-chains, were measured at 260 K and at 101 K a quadrupole doublet of lorentzians with the usual, narrow line width was observed, while at 260 K a superposition was observed of one doublet with a narrow and a second one with a broadened line width. The narrow doublet is attributed to elastic absorption processes and the broadened doublet to quasi-elastic ones. The spectrum at 260 K indicates that fluctuational processes between conformational substates of the quarternary “R” structure do exist.