A. ROSSI-FANELLI 



Finally we compared the arginine/sulphur and histidine/iron ratios 

 of human haemoglobin and myoglobin with those of the corresponding 

 pigments from other species. The results are summarized in Table III. 

 It will be noted that the arginine/sulphur ratio, which Roche con- 

 siders to be very important for the classification of proteins 20 , has a 

 constant value for haemoglobins of different species, and a different 

 constant value for myoglobins of different species ; myoglobin has an 

 arginine/sulphur ratio half that of haemoglobin — another index of the 

 different nature of the two pigments. On the other hand the histidine/ 

 iron ratio, while constant for haemoglobins of different species, is not 

 constant for the different myoglobins. This fact is of particular interest 

 in view of the fact that this amino-acid is believed to have a considerable 

 importance in binding the iron of the prosthetic group to the globin. 



Received August 1948 



REFERENCES 



I Rossi-Fanelli, A. and Travia, L. Boll. Soc. ital. Biol. sper. 15 (1940) 484 

 a _ Arch. Sci. biol. Napoli 26 (1940) 244 



3 — and Travia, L. Boll. Soc. ital. Biol. sper. 16 (1941) 768 



* — and Vescia A. Boll. Soc. ital. Biol. sper. 17 (1942) 291 



5 — and Aragona, C. Boll. Soc. ital. Biol. sper. 17 (1942) 206 



• Roche, J., Derrien, Y. and Vieil, H. Bull. Soc. Chim. biol., Paris 24 (1942) 1016 



7 Drabkin, D. L. Amer. J. med. Sci. 209 (1945) 269 



8 Theorell, H. Arch. Biochem. 12 (1947) 119 



" Rossi-Fanelli, A. and Perri, G. C. Boll. Soc. ital. Siol. sper. 23 (1947) 113 

 10 Morgan, V. E. /. biol. Chem. 112 (1936) 557 



II Cohn, E. J. Physiol. Rev. 5 (1925) 359 



12 Roche, J. and Marquet, F. Bull. Soc. Chim. biol., Paris 17 (1935) 1630 



,3 Boyes-Watson, J., Davidson, E. and Perutz, M. F. Proc. roy. Soc. A. 191 



(1947) 83 

 14 Rossi-Fanelli, A. and Vescia, A. Boll. Soc. ital. Biol. sper. 17 (1942) 129 

 16 Drabkin, D. L. /. biol. Chem. 164 (1946) 703 



,R Rossi-Fanelli, A. and Giulotto, L. Boll. Soc. ital. Biol. sper. 23 (1947) 253 

 't _ Boll. Soc. ital. Biol. sper. 23(1947)852 

 » _ Boll. Soc. ital. Biol. sper. 24 (1948) 410 

 '• — and Giulotto, L. Boll. Soc. ital. Biol. sper. 24(1948)506 

 20 Roche, J. Essai sur la biochemie generate et comparee des pigments respiratoires 



Masson et Cie, Paris 



120 



