532 XI. HEMOGLOBIN CATABOLISM, I 



malian erythrocytes. As has been discussed in Chapter IX, Section 2.7.2., 

 Keilin and Hartree {1500) found however that hydrogen peroxide, slowly 

 formed by certain enzyme systems in small concentrations, produced hemo- 

 globin in the mammalian erythrocyte in spite of the presence of catalase in 

 large amounts. The fact that erythrocyte catalase does not contain bile 

 pigment hematin is also in agreement with the assumption that hydrogen 

 peroxide does not normally reach the erythrocyte. 



Nevertheless, it would be premature to rule out a protection of 

 hemoglob n by catalase under physiological conditions. Lemberg and 

 co-workers {1697) and Engel (689,692) have shown that the forma- 

 tion of verdohemochrome from pyridine hemochrome and the forma- 

 tion of choleglobin from hemoglobin are not prevented by catalase, 

 but that the rate of the reaction is decreased. In the intact erythro- 

 cyte, Keilin and Hartree found no irreversible oxidation of hemo- 

 globin to choleglobin by hydrogen peroxide formed by notatin, while 

 this occurred in hemolyzed blood.* 



The possibility that irreversible destruction of hemoglobin may be 

 accelerated by drugs which inhibit catalase is therefore still more 

 likely than that hemzglobin formation may be increased in this 

 manner {cf. Section 4.2.). It should be noted, however, that the 

 hypothesis of catalase inhibition has been erroneously used to explain 

 the effect of cyanide on pseudohemoglobin formation in vitro 

 (Chapter X, Section 6.1.) or the effect oi sulfide on su If hemoglobin 

 formation. 



5.8. Disintegration of the Dying Cell 



The normal destruction of the erythrocyte has been discussed so 

 far in the literature (cf. the reviews 1381^,2371,2989,3116) generally 

 with regard to the final mechanism of disintegration of the cell 

 rather than with regard to the changes which presage its destruction 

 and end its life. The former may now be regarded in its proper per- 

 spective, as acting under normal conditions on cells which are doomed 

 to die. Under abnormal conditions, the mechanisms of disintegra- 

 tion may, however, act on normal living cells, i.e., cells whose metab- 

 olism has not yet reached its terminal phase. An exponential decay 

 curve may then be found. 



Rapid hemolysis in vitro is brought about by a large number of agents, 

 such as hypotonic solutions, organic solvents, saponins, and hemolysins. 



* Recent evidence {1699; cf. Chapter X, Section 4.4.2.) strongly supports the 

 assumption that catalase protects hemoglobin in the erythrocyte. 



