This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: HAEM synth and porphyrias, Subject name: Biochemistry
Porphyrin of normal erythrocyte haemoglobin is 
Select and explain. 
A. Coproporphyrin I, B. Uroporphyrin III, C. Protoporphyrin III, D. Uroporphyrin I
C: Protoporphyrin III
Answer: C: Protoporphyrin III 
Explanation: Heme is iron containing protoporphyrin. Protoporphyrins are named according to the side chains, i.e. Methyl, vinyl, propionyl.