High Resolution Nuclear Magnetic Resonance Studies of Haemoglobin J Capetown

HAEMOGLOBIN J CAPETOWN 1 is a Hb variant in which one amino-acid in the α-chain, arginine α92 (FG4), is replaced by glutamine. In Hb Chesapeake 2 the same arginine is replaced by leucine, and the properties of the two variants are seen to be similar 2,3 . Compared with normal Hb A, both have increased oxygen affinities, smaller “haem-haem” interactions, and alkaline Bohr effects which are approximately normal. The X-ray crystallography of oxyhaemoglobin at 2.8 Å resolution, shows that the residue α92 (FG4) is at the α1βb2 interface 4 . Perutz and H. L. 5 have pointed out that all known haemoglobin variants with alterations at the α1β2 interface have reduced “haem-haem” interaction.