Heme

Question 1

Structure of Porphyrins

Answer 1

4 5-membered rings w/ Ns facing inwards

Question 2

Beginning of Heme Synthesis

Answer 2

Gly and succinyl CoA joined by ALAS (ALA synthase) 1 and 2 to create ALA

Question 3

Difference b/w Anemia and Porphyrias

Answer 3

Anemia is making heme fine but it has short life
Polyphoria is blockage of heme synthesis pathway, and heme is an inhibitor of ALAS so start synthesizing shitton of intermediates that buildup wherever the blockage is

Question 4

Heme Degradation 1st Stop (3)

Answer 4

Macrophage consumes
Oxidized to biliverdin
Reduced to bilirubin for albumin-mediated transport through blood to liver

Question 5

Bilirubin glucuronyl-transferase

Answer 5

In liver uses 2 UDP-glucuronic acid to convert bilirubin to bilirubin diglucuronide into bile

Question 6

Bilirubin in Intestine (4)

Answer 6

Glucuronic acid removed by bacteria to convert to urobilinogen
Urobilinogen either recycled back to liver, sent to kidneys where it becomes yellow urobilin, or oxidized by gut bacteria to brown stercobilin

Question 7

Hemolytic Jaundice

Answer 7

Something like G6P Dehydrogenase deficiency causes rapid release of heme and liver can’t process fast enough, causing backup of bilirubin into blood

Question 8

Neonatal Jaundice (& cure)

Answer 8

Newborns don’t express bilirubin glucuronyl transferase initially, but premies don’t even have stuff to start. UV light treatment can actually cure

Question 9

Catecholamine Synthesis (6)

Answer 9

Tyrosine hydroxylase (dependent on Tetrahydrobiopterin [BH4]) converts tyr to DOPA -> DA -> NOR -> EPI

Question 10

4 Enzymes that Use BH4

Answer 10

Phenylalanine, tyrosine, and tryptophan hydroxylases

Nitric Oxide Synthase

Question 11

Histamine Synthesis

Answer 11

Histidine decarbox’d

Question 12

5-HT Production (2)

Answer 12

Trp hydroxylase uses BH4 to convert to intermediate, then decarbox’d to 5-HT

Question 13

2 Starting Components for Creatine

Answer 13

Arg and Gly

Question 14

Creatine function

Answer 14

Converted to creatine P for quick reserve to regenerate ATP in muscle

Question 15

Creatine Structure

Answer 15

Acetoguanidino group

Question 16

Creatinine

Answer 16

Intermediate b/w creatine and creatine P used to measure kidney function