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Contribution of α140Tyr and β37Trp to the near‐UV CD spectra on quaternary structure transition of human hemoglobin A
Author(s) -
Li Renqiang,
Nagai Yukifumi,
Nagai Masako
Publication year - 2000
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/(sici)1520-636x(2000)12:4<216::aid-chir8>3.0.co;2-4
Subject(s) - chemistry , deoxygenation , crystallography , protein quaternary structure , hemoglobin , mutant , spectral line , chirality (physics) , protein subunit , stereochemistry , catalysis , biochemistry , physics , astronomy , gene , chiral symmetry breaking , quantum mechanics , nambu–jona lasinio model , quark
The CD band of human adult hemoglobin (Hb A) at 280 ∼ 290 nm shows a pronounced change from a small positive band to a definite negative band on the oxy (R) to deoxy (T) structural transition. This change has been suggested to be due to environmental alteration of Tyrs (α42, α140, and β145) or β37 Trp residues located at the α1β2 subunit interface by deoxygenation. In order to evaluate contributions of α140Tyr and β37Trp to this change of CD band, we compared the CD spectra of two mutant Hbs, Hb Rouen (α140Tyr→His) and Hb Hirose (β37Trp→Ser) with those of Hb A. Both mutant Hbs gave a distinct, but smaller negative CD band at 287nm in the deoxy form than that of deoxyHb A. Contributions of α140Tyr and β37Trp to the negative band at the 280 ∼ 290 nm region were estimated from difference spectra to be 30% and 26%, respectively. These results indicate that the other aromatic amino acid residues, α42Tyr and β145Tyr, at the α1β2 interface, are also responsible for the change of the CD band upon the R→T transition of Hb A. Chirality 12:216–220, 2000. © 2000 Wiley‐Liss, Inc.