Changes of tyrosine and tryptophan residues in human hemoglobin by oxygen binding: near- and far-UV circular dichroism of isolated chains and recombined hemoglobin

摘要: Abstract In order to assign the circular dichroism (CD) spectral change in region between 280 and 300 nm of human adult hemoglobin (Hb A) upon quaternary structure transition induced by oxygen binding, near- far-UV CD spectra isolated chains recombined were examined. Deoxygenation made negative band at 290 oxy-α chain deeper. On other hand, positive bands oxy-β 280∼300 became deoxygenation. These changes interpreted as being due environmental alterations tyrosine (Tyr) and/or tryptophan (Trp) perturbed tertiary structural from oxy deoxy form chains, referring model compounds. From difference arithmetic mean deoxyHb tetramer, contribution A 287 was estimated be 50%. This finding has revealed that net is spectra, aromatic residues also detected a 225 nm.