90 



K. Kaziro and K. Tsushima 



alkali-denatured protein should therefore be twice the number of bound 

 haem molecules. The results of this type of experiment with various kinds of 

 protein are summarized in Table 3. In the case of haemoglobin, apparently 



0-5 



2 3 4 5 6 



Hoem added, xlCJ^ M 



Fig. 8. Haemochrome formation of alkali-denatured haemoglobin with added 



haem. In this Fig., and in Figs. 10 and 12, the haem concentrations shown on the 



abscissa are amounts added, over and above the haem associated with the original 



denatured haemoglobin. 



Table 3. Basic amino acid content and the haem BiNorNO groups 



53 % of the total nitrogen-base residues of the globin moiety can bind haem 

 and the number is far beyond the total histidine content of haemoglobin. 

 The results of these experiments are rather surprising when we recall that the 

 affinity of haem to various amino acids is usually not so high, and especially 

 that almost no haemochrome can be obtained by the reaction of free haem 

 and free amino acids at such a high pH as used in the present experiments. 



