Heat denaturation of metHb and HbNO: e.p.r. evidence for the existence of a new hemichrome.
Electron paramagnetic resonance was used to follow the time dependence of heat denaturation of met- and nitrosyl-haemoglobin (metHb and HbNO) at 60 degrees C, 70 degrees C and 80 degrees C. The spectral changes of both complexes indicate that conformational changes in the protein manifest themselves in changes of the equilibrium of hemichromes in metHb and of six- and five-coordinated iron in HbNO. The formation of a hemichrome which has not been described before, with g = 2.45, 2.27 and 1.85, is observed. A His-Fe-Cys complex is proposed for its structure.
Alves
O C
OC
Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro, Brazil.
Wajnberg
E
E
D004578:Electron Spin Resonance Spectroscopy; D006418:Heme / Q000737:chemistry; D006454:Hemoglobins / Q000737:chemistry*; D006801:Humans; D008706:Methemoglobin / Q000737:chemistry*; D008958:Models, Molecular; D011487:Protein Conformation; D011489:Protein Denaturation; D013696:Temperature
D006454:Hemoglobins; C008657:nitrosyl hemoglobin; D006418:Heme; D008706:Methemoglobin