FELIX HAUROWITZ 



and oxygen according to the classical monomolecular equation 



HbO a ^ Hb + 2 , 

 but that this reaction takes place according to the bimolecular equation 

 Hb0 2 + H 2 ^ Hb(H 2 0) + 2 . 

 It is obvious that both equations lead to the same results in dilute 

 aquous solutions, because in such solutions the excess of water mole- 

 cules is so large that the water concentration remains practically 

 constant during the reaction. Differences may arise, however, in very 

 concentrated solutions of oxyhaemoglobin or in wet haemoglobin 



crystals. e 



The new equation renders understandable the large influence ot 

 salts, hydrogen ions and proteins on the equilibrium between haemo- 

 globin and oxygen. For all these substances are polar hydrophyhc 

 substances and are able to act by means of Coulomb forces on the 

 iron-linked water molecule of haemoglobin. It is evident that such an 

 action will modify the affinity of oxygen for the haemoglobin molecule. 

 For the same reason the globins of different species, containing different 

 hydrophylic groups in the environment of the iron-bound water 

 molecule, will have a different influence on this water molecule and 

 thus will alter the equilibria between haemoglobin and oxygen. Indeed 

 it has been demonstrated by Barcroft 7 that the affinity of 2 to the 

 haemoglobin molecule varies with the species specificity of globin. For 

 the same reason this affinity is different in maternal and m foetal 

 haemoglobin 8 ' 9 and undergoes an alteration upon haemolysis of the 

 red blood corpuscles 8 ' 9 . It is hardly possible to explain this latter 

 phenomenon by the classical equation. But it is understandable 

 according to the new equation and Formula II that the affinity of the 

 iron-linked water molecule to the Fe atom is altered as soon as the 

 electrostatic influence of closely adjacent protein or lipid molecules on 

 the iron-linked water molecule is abolished by haemolysis. 

 Received July 1948 



REFERENCES 



1 Haurowitz, F. Hoppe-Seyl.Z. 232(1935)146 



2 V Zeynek, R. Nowiny Lekarske Poznan 38 (1925) 1U 



3 Granick, S. J. gen. Physiol 25(1942)571 



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



■ Pauling, L. and Coryell, C. Proc. nat. Acad. Sci. Wash. 22 (1936) 159 



• Theorell, H. J. Amer. chem. Soc. 63(1941)1820 n <v>jr>« 1R 

 » Barcroft, J. The Respiratory Function of the Blood ^Cambridge (1928) p. 38 

 8 Haurowitz, F. Hoppe-Seyl.Z. 183(1929)78; 186(1930)141 



• McCarthy, E. /. Physiol. 102 (1943) 55 



56 



