THE DISSOCIATION CURVE OF HEMOGLOBIN 103 



under quite rigid conditions at — 1° C, the more closely would the 

 curve derived from it be to the hyperbola — and that is a curious 

 thing ! 



That seems to be the position as regards dilute haemoglobin solu- 

 tions ; really concentrated ones never seem to give the hjrperbola. 



Carbon monoxide forms a reversible compound with haemo- 

 chromogen, the dissociation curve of which has been studied by Anson 

 and Mirsky(i2). They found it to be definitely a rectangular hyper- 

 bola, the hsemochromogen being 50 per cent, saturated at 37° C. when 

 exposed to a pressure of carbon monoxide of jf^ mm. (see Fig. 30). 



If then we may regard the fundamental difference between haemo- 

 chromogen and haemoglobin as being the different condition in which 

 the globin is found in the two substances, we should be directed 

 towards the conclusion that where the protein is in the denatured 

 state the curve is a hyperbola, and in so far as the curve differs from 

 the hyperbola in the case of haemoglobin the difference is imposed by 

 the protein. 



We have yet to learn the molecular weight of hsemochromogen and 

 it may be much less than that of haemoglobin, a difference which also 

 might influence the shape of the curve. 



The important point is that the most primitive dissociation curve 

 of which we know, that from which the other curves appear to be 

 derived, is indeed a hyperbola. 



REFERENCES 



1) HtJPNER. Arch. f. Anat.u. Physiol. V. 1S7. 1901. 



2) Bohr. Zentralb. f. Physiol, xvn. 682. 1879. 



3) Babcroft and Camis. Journ. Physiol, xxxix. 118. 1909. 



4) Barcroft and Roberts. Journ. Physiol, xxxix. 143. 1909. 



5) Adolf and Ferey. Journ. Biol. Chem. XLvn. 547. 1921. 



6) Adair, Barcroft and Bock. Journ. Physiol, lv. 332. 1921. 



7) Adair. Fellowship Dissertation presented to King's College, Cambridge, 1921. 



8) Hartridge and Roughton. Proc. Roy. Soc. A. civ. 398. 1923. 



9) Hartridge and Rouohton. Proc. Boy. Soc. A. cvn. 673. 1926. 



(10) Barcroft. Journ. Chem. Soc. cxxix. 1146. May, 1926. 



(11) Hecht AND Morgan. In press. 



(12) Anson AND Mirsky. Journ. Physiol. i.x. 63. 1925. 



