The thermal denaturation of human oxyhaemoglobins A, A2, C and S.
1. The time-courses of thermal denaturation of human oxyhaemoglobins A, A(2), C and S at 45 degrees C were studied by following the increase in protein fluorescence. Haemoglobins S and C were less stable than haemoglobin A, whereas haemoglobin A(2) was considerably more stable. 2. The time-courses of denaturation did not follow first-order kinetics and could be fitted most simply to a co-operative scheme in which the partial denaturation of the alpha chain preceded that of the beta chain. 3. The denaturation of these haemoglobins was studied as a function of temperature by using optical rotatory dispersion. Haemoglobin A(2) was again more stable than the others. The addition of small quantities of haemoglobin A(2) had a disproportionate effect on the stability of haemoglobin C. 4. The thermodynamic parameters of the denaturation process were calculated.
D006444:Hemoglobin C; D006451:Hemoglobin, Sickle; D006454:Hemoglobins; D006358:Hot Temperature; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009904:Optical Rotation; D010108:Oxyhemoglobins; D011489:Protein Denaturation; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics; D013997:Time Factors
D006451:Hemoglobin, Sickle; D006454:Hemoglobins; D010108:Oxyhemoglobins; D006444:Hemoglobin C