Mark the false statement among given options related to heme :
**Core Concept**
The heme biosynthetic pathway involves a series of enzyme-catalyzed reactions that convert succinyl-CoA and glycine into heme, a crucial component of hemoglobin, myoglobin, and various cytochromes. This complex pathway is tightly regulated to ensure proper heme homeostasis.
**Why the Correct Answer is Right**
The correct answer involves identifying a false statement among the options. To do this, we must understand the key steps and enzymes involved in the heme biosynthetic pathway. The pathway begins with the condensation of succinyl-CoA and glycine to form δ-aminolevulinic acid (ALA), which is then converted into porphobilinogen (PBG) by the enzyme ALA dehydratase. PBG is subsequently converted into uroporphyrinogen III by the enzyme porphobilinogen deaminase. This step is crucial, as the incorrect formation of uroporphyrinogen III can lead to the accumulation of toxic porphyrins.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the correct enzyme involved in the heme biosynthetic pathway. While ALA synthase is involved in the pathway, it is not the enzyme responsible for the conversion of PBG to uroporphyrinogen III.
**Option B:** This option is incorrect because it does not accurately describe the conversion of PBG to uroporphyrinogen III. The correct enzyme involved in this step is porphobilinogen deaminase, not porphobilinogen oxidase.
**Option C:** This option is incorrect because it does not specify the correct intermediate in the heme biosynthetic pathway. While uroporphyrinogen I is an intermediate in the pathway, it is not the correct intermediate formed from PBG.
**Option D:** This option is incorrect because it does not accurately describe the role of coproporphyrinogen III oxidase in the heme biosynthetic pathway. This enzyme is involved in the conversion of coproporphyrinogen III to protoporphyrin IX, not in the conversion of PBG to uroporphyrinogen III.
**Clinical Pearl / High-Yield Fact**
A deficiency in the enzyme porphobilinogen deaminase can lead to acute intermittent porphyria, a rare genetic disorder characterized by the accumulation of toxic porphyrins. This condition can cause severe abdominal pain, neurological symptoms, and even life-threatening complications.
**Correct Answer: C.**