Q5(c). Oxidation of haem to hematin, and how the protein prevents it
Give the mechanism of fatal formation of hematin in the binding of dioxygen by heme. How can it be averted by living systems?
Answer in brief
A second haem attacks the O₂ bound to a bare haem, and the Fe–O–O–Fe bridge breaks up to the μ-oxo dimer PFe(III)–O–Fe(III)P, hematin, which cannot carry O₂; globin buries each haem in a non-polar pocket so two haems never meet.
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Covershematinhaem oxygen bindingμ-oxo dimermyoglobinpicket-fence porphyrinsite isolation
All parts of Question 5
- 5(a) Rate constant and half-life of a zero-order reaction10 marks
- 5(b) Lambert–Beer law: statement and derivation10 marks
- 5(c) Oxidation of haem to hematin, and how the protein prevents it10 marks
- 5(d) Geometrical isomers and stereoisomers of M(AB)b₂c₂10 marks
- 5(e) Completing five reactions of xenon compounds10 marks