Heme Metabolism

Question 1

What is heme important for

Answer 1

Major part of hemoglobin, also myoglobin, cytochromes, CYP450, peroxidases and NO synthesis

Question 2

What is porforin

Answer 2

Heme without iron

Question 3

What are prophyrias

Answer 3

Inherited defects in heme synthesis

Question 4

Intermediates in heme synthesis

Answer 4

Pyrole a 4 carbon ring with a Nitrogen
Bilirubin (multiple pyrole’s together)
Porphyrin - bilirubin in a ring
Heme - porphyrin with fe in the middle

Question 5

How do we make heme

Answer 5

Glycine and succinyl coa combine to form g-aminolevulinic acid (ALA) with the help of ALA synthase which then is changed to porphobilinogen with the help of ALA dehydrogenase and then that goes to protoporphyrin and then heme

Question 6

Regulation of heme synthesis

Answer 6

ALAS is inhibited by end products (heme) - end product feedback inhibition
ALAD is Zn dependent

Question 7

Signs of porphyria

Answer 7

Skin rash, photosensitive, abdomen pain, neuropsych symptoms, dark urine

Question 8

Types of porphyria

Answer 8

Erythropoietic

Hepatic (acute or chronic)

Question 9

What precipitates acute hepatic porphyria

Answer 9

Drugs (barbiturates, Etoh)

Stressors

Question 10

Heme degradation

Answer 10

Heme is degraded to biliverdin them to bilirubin (which can cause jaundice)