A Solubility Study of Foetal and Adult Sheep Haemoglobin 



ponents are calculated according to the diagrams, it is found that they 

 are in the following relation to each other : 



pU 



7-2 



5-9 



4-6 



Solubility of A 



1/1-92 



1/1-72 



1/1-14 



Solubility of B 



The jpH- solubility graphs are, therefore, essentially parallel, and do 

 not differ as much as, e.g., those of the foetal and maternal Hb. When 

 the composition of the mixture is calculated according to the three 

 diagrams, the following percentages are obtained : 



pH 7-2 5-9 4-6 



Percentage of A 12% 19% 20% 



Percentage of B 



° 



/o 



81% 



80% 



O 5 10 



Total Hb am/ '/OOO cc 



Figure 4. The solubility of a sample of sheep 



foetal Hb in three solvents, with varying total 



Hb concentration. Equilibration from the 



undersaturated side. 



The agreement between these three values is to be regarded as satisfactory. 

 That the proportion of the components is not essentially affected by 

 great variations in the pU, makes it probable that the components are 

 preformed and not artifacts. 



Until the 120th day of foetal life the precipitate had been composed 

 of one type of crystals only, greatly different from those of the adult. 

 During the last month of the foetal life and the first month of post- 

 natal life the precipitate became irregular, sometimes amorphous 

 (possibly microcrystalline), and crystals of the adult type began to 

 appear. Simultaneously with this change in the appearance of the 

 solid phase, the solubility of the Hb samples increased. The solubility 

 was often, however, much higher than could be accounted for by 

 assuming, that foetal and adult Hb were present as a mixture, each 

 component showing an additive solubility. 



283 



