186 V. HEMATIN COMPOUNDS 



has been studied by Clifcorn and collaborators (4^56). Their value 

 for the dissociation constant of carbon monoxide from carbon mon- 

 oxide pyridine hemochrome (1.24 X 10*) unfortunately cannot be 

 compared exactly with the dissociation constant of denatured globin 

 carbon monoxide hemochrome of Anson and Mirsky (1.63 X 10" ), 

 since the former was measured at 25°, the latter at 36.5° C. The 

 carbon monoxide, however, appears to be more firmly bound to the 

 denatured globin hemochrome. 



Absorption spectra of carbon monoxide hemochromes are of special 

 interest, since the photochemical spectrum of the respiratory ferment 

 is actually that of its carbon monoxide compound, and belongs to 

 this class. The absorption spectrum of denatured globin carbon 

 monoxide hemochrome is the same as that of carbon monoxide 

 hemoglobin, having bands at 570 and 540 m^ (1276,24.55), the second 

 being slightly higher. 



Warburg and collaborators {2957) have attached great significance 

 to the position of the Soret band as an indication of the type of 

 porphyrin present in carbon monoxide hemes and hemochromes. 

 That such is not necessarily the case is shown by the fact that, on 

 the one hand, carbon monoxide compounds containing the same heme 

 but different nitrogenous bodies sometimes show differences in the 

 position of the Soret band (c/. Keilin, 1479), while, on the other, 

 compounds containing different hemes show identical positions. These 

 relationships will be clear from Table VI. 



TABLE VI 



Spectroscopic Data for Carbon Monoxide Compounds 



Soret band Other bands 



Substance m/u CmM m^ fmM Ref. 



COprotoheme 415 158 543 14.6 621,29 5 



578 15.1 2Jt55 



CO spirographis heme 410 7'97 



CO chlorocruorin 440 132Jt 



CO pyridine protohemochrome 440 132 Jt 



CO hydrazine protohemochrome 410 'ifdl 



There is still need for a systematic study of carbon monoxide 

 hemochromes, particularly those containing imidazole as the coordi- 

 nating base. 



