Heme Synthesis

Question 1

What enzyme performs the rate-limiting step of Heme Synthesis?

Answer 1

ALA synthase

Question 2

Which two substances are needed to start heme synthesis?

Answer 2

Sunncinyl CoA and Glycine

Question 3

Which enzyme in Heme synthesis needs Vitamin B6 as a co-factor?

Answer 3

ALA Synthase

Question 4

Which 2 substances provide negative feedback to ALA Synthase?

Answer 4

Glucose and Heme

Question 5

What is the fate of ALA in heme synthesis? Which enzyme is needed for this?

Answer 5

ALA gets converted to Porphobilinogen via the enzyme ALA dehydratase

(Alladin tasing poor bill)

Question 6

How does lead inhibit heme synthesis?

Answer 6

Lead inhibits ALA dehydraTASE and Ferrochelatase

Question 7

What is fate of porphobilinogen?

Answer 7

Poor bill’s dam falling into the bike lane.

Prophinobilinogen gets converted hydroxymethylbilane via porphobilinogen DEAMINASE.

Question 8

Which enzyme is defective in Acute intermittent Porphyria?

Answer 8

Porphobilinogen deaminase

Question 9

Defective enzyme in Porphyria Cutanea Tarda?

Answer 9

Uroporphyrinogen decarboxylase is defective. It converts uroporphyrinogen 3 into Copro-porphyrinogen

Question 10

Location of different reaction of heme synthesis?

Answer 10

First and last reactions occur in mitochondria, the rest in cytoplasm

Question 11

Treatment of porphyria cutanea tarda?

Answer 11

Phelebotomy, Hydroxychloroquine and Sun-avoidance

Question 12

Which porphyria causes Tea-colored urine and due to the accumulation of which substance?

Answer 12

Porphyra cutanea Tarda,

Due to accumulation of uroporphyrinogen.

Question 13

What exacerbates Acute Intermittent Porphyria?

Answer 13

Cytochrome p450 inducers, alcohol.