Crystallization and Solubility Studies on 

 Human Adult and Foetal Haemoglobins 



H. M. JOPE and J. R. P. O'BRIEN 



The crystallization and solubility behaviour of human adult and 

 foetal haemoglobins, carbonmonoxyhaemoglobin (HbCO), oxy- 

 haemoglobin (Hb0 2 ), methaemoglobin (MetHb) and ' reduced ' 

 haemoglobin (Hb), have been studied under varying conditions. 



A method is given for the crystallization of adult and foetal 

 HbCO, HbO,, MetHb and Hb on a scale sufficiently large for use 

 in solubility measurements. 



Adult HbCO, HbO 2 and MetHb crystals are isomorphous and 

 belong to the orthorhombic system ; foetal HbCO, Hb0 2 and 

 MetHb are also isomorphous but crystallize in a system different 

 from that of the adult derivatives, probably triclinic. HbCO, Hb0 2 

 and MetHb, both adult and foetal, crystallize in systems different 

 from that of the corresponding Hb. 



Human adult haemoglobin appears from solubility, electro- 

 phoresis and ultracentrifuge data to be a homogeneous protein. 

 Amorphous HbCO is more soluble than crystalline HbCO. HbCO, 

 Hb0 2 and MetHb, both adult and foetal, are more soluble than 

 the corresponding Hb. Adult HbCO, Hb0 2 and MetHb have 

 different types of solubility-temperature curves from those of foetal 

 HbCO, Hb0 2 and MetHb. Adult and foetal Hb's have very 

 similar solubilities, which do not vary with temperature. There is, 

 therefore, in both crystal form and solubility behaviour, a clear 

 distinction between Hb on the one hand and HbCO, Hb0 2 and 

 MetHb on the other, and also between the adult and foetal 

 haemoglobins. 



INTRODUCTION 



The possibility of obtaining human haemoglobin in crystalline form 

 has now been recognised for a century (F. L. Hunefeld 1 and O. Funke 2 

 give drawings of Hb crystals), but it is only in recent years that this 

 crystalline form has been exploited to study its behaviour and mole- 

 cular structure. E. T. Reichert and A. P. Brown 3 , G. Amantea 4 

 and C. Perrier and P. Janelli 5 obtained human haemoglobin crystals 

 on a micro scale and described them but gave no photographs. F. 

 Haurowitz 6 prepared crystals of human adult and foetal haemoglobins 

 and published a photograph of adult haemoglobin crystals from salt- 



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