206 Essays in Biochemistry 



Although this method does not yield data for the absolute amount 

 of ferrous iron in ferritin it was found useful for comparative purposes. 

 From this data it can be calculated that active ferritin can contain 

 at least 0.2% of its total iron in the form of ferrous iron. 



Repetition of our earlier experiments to include ferrous iron analyses 

 indicated that whenever sulfhydryl groups increased ferrous iron also 

 increased, and vice versa (Table 6). Further, iodoacetamide ferritin 



Table 6. Effect of Liver Slices on Sulfhydryl Groups and Ferrous Iron 



of Ferritin 



SH Fe++ 



Ferritin Treatment yuM per 100 mg. ferritin N 

 Original ferritin 25 . 1.7 



(a) Ferritin + liver slices in N 2 33 . 7 6.5 



(b) (a) + liver slices in 2 14.9 2.3 



A. Mazur, S. Baez, and E. Shorr, J. Biol. Chem.. March. 1955. 



after treatment with cysteine, ascorbic acid, or glutathione showed 

 marked increases in ferrous iron content (Table 7 and 8). Finally, 



Table 7. Effect of Reducing Agents on Ferrous Iron of Ferritin 



Ferrous Iron 



A. Mazur, S. Baez, and E. Shorr, J. Biol. Chem., March, 1955. 



Table 8. Effect of Reducing Agents on Iodoacetamide-Treated Ferritin 



SH Ferrous Iron 



A. Mazur, S. Baez, and E. Shorr, J. Biol. Chem., March, 1955. 



