Isoelectric points, haemoglobins

Figure 14.1 [6]. Only for pHs below the isoelectric point (pi) of the protein should the protein be extracted with anionic surfactants such as DOLPA or AOT, whereas for pHs above the pi, extraction into the reverse micellar phase should be inhibited because of the unfavourable electric repulsion. This result indicates that electrostatic interactions are required to extract haemoglobin efficiently into reverse micelles.

The isoelectric points of the various haemoglobins also show differences (see Table XV). 

As can be seen from the Table, vertebrate haemoglobin has an isoelectric point around neutrality and differing from that of other tj es of haemoglobin whose isoelectric points are more add. 

---