Preparation of Hybrid Hemoglobins with Different Prosthetic Groups

This chapter describes the preparation of hybrid hemoglobins with different prosthetic groups. The methods of preparation of artificial hemoglobins containing unnatural hemes or other metalloporphyrins are examined briefly. The properties of these artificial hemoglobins have to be checked before preparing the isolated chains. The oxygen-equilibrium-curve measurement is the most effective method to evaluate the quality of the preparation. An automatic-equilibrium-curve recording system—such as the Imai apparatus, which enables one to cover a wide range of saturation—is quite suitable for this purpose. As iron hemoglobins with unnatural hemes are usually prepared in the Met(Fe³⁺) form, the metal ion has to be reduced to the ferrous state for study of their functional properties. This can be carried out easily by the use of the enzymic methemoglobin–reducing system in place of sodium dithionite or sodium borohydride. The preparation of −pMB chains are also described in the chapter.