R. R. PORTER and F. SANGER 

 COMPARATIVE STUDY OF THE HAEMOGLOBINS 



Table I summarises the results that were obtained using the DNP 

 technique. 



Table I. The Numbers of Free Amino Groups of Haemoglobins 



It can be seen from these results that the haemoglobins from closely 

 related animals, such as the horse and donkey or the cow, sheep and 

 goat have the same number of open polypeptide chains per molecule 

 and that these chains have the same terminal amino-acids, although 

 the two groups are distinct from each other and from the other 

 haemoglobins examined. A detailed investigation of the serological 

 relationships of these proteins has been carried out 4, 5> 6 and it was 

 found that the haemoglobins from the closely related animals, which 

 we have now shown to have a similar structure, cross-reacted strongly 

 with each other but not with other haemoglobins. Also L. Hetkoen 7 

 found in the dog that myoglobin was serologically distinct from haemo- 

 globin and R. R. Darrow, S. Nowakovsky and M. H. Austin 8 showed 

 that human adult and foetal haemoglobin did not cross-react. Thus 

 the parallel between the immunological behaviour of the haemoglobins 

 and the general structure as revealed by this technique is striking. It 

 may be, however, that though both these properties are dependent on 

 the genealogical origin of the proteins, they are not interdependent. 

 A much more detailed study would be necessary to establish the 

 precise features of the protein structure which control immunological 

 specificity. 



Preliminary investigations of serum globulins 9 showed that there 

 were similar structural variations from species to species and it would 

 be interesting to know if this could be a basic property of all proteins. 

 Insulin has indeed been found to be an exception in that cattle, sheep 



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