A Solubility Study of Foetal and Adult 

 Sheep Haemoglobin 



M. J. KARVONEN* 



The solubility of sheep foetal and adult haemoglobin was investigated 

 in buffered ammonium sulphate solutions. The effect of three 

 variables, pH, salt and protein concentrations, was tested. The 

 results were interpreted as indicating that both foetal and adult Hb 

 were composed of two nearly related components. The transition 

 from the foetal to the adult type occurred during the last month of 

 foetal life and the first month of post-natal life. The mixtures of the 

 adult and foetal type HVs showed solubilities which were more than 

 additive. An approximate method was developed for assessing their 



composition. 



Differences exist between the solubilities of adult haemoglobin and 

 foetal haemoglobin (Hb). G. Zanier 1 in the course of haemolysis 

 experiments observed, that foetal calf haemoglobin started to pre- 

 cipitate at lower NaCl concentrations than those needed for the Hb. 

 of the adult cow. Recently J. Wyman, J. A. Rafferty and E. N. 

 Ingalls 2 have studied the salting out of foetal calves' Hb with strong 

 phosphate buffers. The solubility of the Hb was investigated in a 

 constant solvent, and the equilibrium was approached from the super- 

 saturated side. Under the conditions of the study the foetal Hb was 

 much more soluble than the adult. Both Hb's, however, showed a 

 rather anomalous solubility ; a further increase of the protein con- 

 centration in the system beyond the onset of crystallization resulted 

 in a great and rapid decrease in the solubility. This anomaly made 

 it impossible to draw any conclusions as to the homogeneity either of 

 the foetal or of the adult cow Hb. 



The programme of the present work has been to follow the solubility 

 of sheep Hb from early midfoetal up to adult life. The Hb of adult 

 sheep has also been investigated. Both the ' variable solvent ' — or 

 salting out — and the ' constant solvent ' methods have been used. 

 An attempt has been made to give the — often anomalous — results of 

 the solubility measurements a physico-chemical interpretation and to 

 correlate the findings with the physiology of the foetus. 



* Present address : Institute of Physiology, Helsinki University 

 279 



