PROTECTION OF HEMOGLOBIN IN THE ERYTHROCYTE 531 



5.7. Protection of Hemoglobin in the Erythrocyte 



There can be little doubt that in vertebrates hemoglobin is pro- 

 tected from rapid irreversible destruction by its incorporation in the 

 red cell. The limited permeability of the cell wall prevents hemo- 

 globin from diffusing into the intracellular spaces, where it would 

 come into contact with potentially harmful systems, and may also 

 prevent harmful substances from diffusing into the cell. It is well 

 known that oxyhemoglobin injected intravenously or set free from 

 the corpuscles by hemolysis carries oxygen only for a few hours and 

 is broken down to bile pigment. It is of interest in this connection 

 that Mouchet {1993) observed that certain blood-sucking parasites 

 of fish (Gnathidae) were able to form bile pigments only when they 

 are able to hemolyze cells of the particular animal to which they are 

 attached. 



The red cell wall does not appear completely impermeable, how- 

 ever, to harmful substances, e.g., ascorbic acid. Of equal importance 

 is probably the presence of factors which Lemberg and co-workers 

 {1710) found to inhibit the reaction between oxyhemoglobin and 

 ascorbic acid in laked horse erythrocytes (c/. Chapter X, Section 

 4.4.2.). 



A similar factor maj' protect the hemoglobins of certain inverte- 

 brate species (erythrocruorins) which contain extracellular hemo- 

 globin. Thus, Salomon {21^23) has shown that the erythrocruorin of 

 Lumbricus is unable to undergo coupled oxidation with ascorbic 

 acid. It is also possible, however, that the inability to react in this 

 manner is a specific property of erythrocruorins {cf. Chapter VII). 



In view of the role which hydrogen peroxide can play in the break- 

 down of hemoglobin {cf. Chapter VIII, Section 6.3.4.; Chapter X, 

 Sections 4.4.1., 4.4.5., and 2.5.), the presence of catalase in the 

 erythrocyte in high concentrations suggests that this enzyme may 

 function as the protective agent. 



Bingold {270-273), particularly, has attempted to prove that the function 

 of catalase in the red cell is the protection of hemoglobin against destruction 

 by hydrogen peroxide. His experiments, however, were carried out with 

 hydrogen peroxide in unphysiologically high concentrations, which causes 

 an unphysiological breakdown of hemoglobin to colorless products. These 

 experiments do not lend strong support to his hypothesis. Still less con- 

 vincing is his assumption that separation of catalase from hemoglobin in the 

 kidney causes hemoglobin breakdown. 



According to Shapot {251^0) hydrogen peroxide oxidizes hemoglobin to 

 hemrglobin in avian corpuscles, which are poor in catalase, but not in mam- 



