PROTEIN METABOLISM 



471 



for an adult human being compared to as much as 250 mg. in feces. 

 Various abnormalities of liver function may block excretion of the 

 bile and cause the accumulation of bile pigments, a disease called 

 jauntUce. Hemolytic jaundice, infectious hepatitis, cirrhosis of the 

 liver, and obstruction of the bile passages are the most common 

 ailments of this type. 



The bile pigments appear as follows. When the red cell is destroyed, 

 the methene carbon ( — CH group) is removed from between the right- 

 hand pyrrole rings of the porphyrin structure. The resulting molecule 

 is called verdoglobin and is still attached to the protein and still 

 contains iron. This material then loses its iron and is split from the 



Verdoglobin 



globin + 



CH 



CH, 



CH 



COOH COOH 

 I I 



CHg (CH2)2 (CH2)2 CHg 



CH. 



iron 



ferritin 

 (storage) 



CH2 



nCH 

 -OH 



biliverdin (green) 



protein, forming biliverdin, a chain of pyrrole rings. This pigment 

 is reduced to bilirubin (orange) which appears in the plasma in 

 complexes with serum albumin and globulins. The liver traps the 

 pigment and excretes it through the bile ducts into the duodenum of 



COOH COOH 



CHo 



CH2=CH CHg (CH2)2 (CH2)2 CHg CHg CH 



bacteria 



bilirubin 



COOH COOH 



CHg C2H5 CHg (CH2)2 (CH2)2 CHg CHg C2H5 



HO^- 



OH 



