Open AccessMEASUREMENT OF LIGAND-INDUCED CONFORMATIONAL CHANGES IN HEMOGLOBIN BY CIRCULAR DICHROISM
Author(s) -
Sanford R. Simon,
Charles R. Cantor
Publication year - 1969
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.63.1.205
Subject(s) - cooperativity , circular dichroism , chemistry , crystallography , hemoglobin , saturation (graph theory) , ligand (biochemistry) , biochemistry , receptor , mathematics , combinatorics
The UV circular-dichroism spectra of human and horse hemoglobins have been determined at various degrees of partial saturation with oxygen. Spectra of the two native hemoglobins were compared with spectra of the corresponding proteins modified with a reagent known to eliminate the conformational rearrangement normally associated with cooperativity. Such comparison indicates that one region, around 260 mμ, is sensitive chiefly to the state of the hemes; changes in another region, around 285 mμ, may be correlated with the conformational transformation linked to cooperative interactions. All circular-dichroism changes are strictly linear with fractional saturation with oxygen. Possible implications of these results to recently proposed mechanisms for cooperativity in proteins are discussed.