Studies on Mammalian Red Cells 81 



isolated between 12 hours and two weeks converge to a value 

 of eight, the earliest samples showing ratios of 5-7. 



5. In these experiments radioactive DL-valine was also 

 administered and valine was isolated from terminal and non- 

 terminal positions of the globin. The radioactivities of the 

 two fractions were identical for each point in time. The 

 radioactivities of glycine and valine were also compared and 

 varied by not more than 20 per cent. These results suggest 

 that the haemoglobin molecule is synthesized either by syn- 

 chronized condensation of amino acids, or by a rapid succes- 

 sive formation of peptide bonds, without any appreciable 

 accumulation of intermediates. 



The experimental work reported was done mainly by my colleagues Dr. 

 Helen Muir and Dr. J. C. Perrone. 



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