The oxygen affinity of haemoglobin Hammersmith.

Oxygen dissociation studies were carried out on red cells and lysates from a patient heterozygous for Hb Hammersmith. The oxygen affinity of the cells at pH 7.1 was decreased, partly by an increased cellular concentration of 2,3-DPG and more importantly by an intrinsic low affinity of Hb Hammersmity. Haem-haem interactions were reduced and an abnormal Bohr effect (pH 7.1-7.4) was found in the cells which would bring about an additional decrease in oxygen affinity at physiological pH. Oxygen dissociation studies on the lysates showed a low oxygen affinity, a normal Bohr effect at 50% saturation, slightly decreased haem-haem interactions and a normal interaction with 2,3-DPG. Estimation of the percentage of Hb Hammersmith in the lysates of the patient's cells by selective precipitation of the abnormal beta chain with p-chloromercuribenzoate (PCMB) showed the presence of 30-33% abnormal haemoglobin. Assuming no interaction between the Hb A and the Hb Hammersmith, oxygen dissociation curves were calculated for Hb Hammersmith alone and these indicated that it has greatly decreased oxygen affinity, a normal Bohr effect, normal 2,3-DPG interaction and (somewhat) decreased haem-haem interactions.