Chapter 15.7, Problem 2QQ

Interpretation Introduction

Interpretation: To determine the incorrect statement concerning the bile pigments produced from the degradation of the heme portion of hemoglobin.

Concept introduction: Hemoglobin is a heme protein present in the red blood cells. The protein part is called globin and the non-protein part is heme. Heme is the prosthetic group that contains 4 pyrrole groups bonded together and has an iron atom in the center. The structure of the heme group is:

Degradation process of heme portion of hemoglobin involves two steps.

Step 1: The first step of degradation of heme involves opening of pyrrole ring with the release of the iron atom. The iron atom released becomes part of ferritin protein.

Step 2: Biliverdin produced is converted bilirubin in the spleen. Bilirubin is then transported to the liver where attachment of sugar residues to the propionate side chains of the bilirubin occurs to make it more soluble.

Then more solubilized bilirubin is excreted in bile and finally to the small intestine. In the small intestine, it is converted into stercobilin for excretion in feces or urobilin for excretion in urine.