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.
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This work was supported by the Deutsche For-scchkunnogwsleGdegmeseitnhsechawafat.rdOnoef aonf Ausle(xKa.nHd.eMr .v)ognraHteufmul-ly boldt Fellowship during his stay in the Federal Republic of Germany.