Final: Lecture 32

Question 0

Important enzymes of Heme Synthesis

Answer 0

A-ALA dehydratase

B-porphobilinogen deaminase

C-uroporphyrinogen III synthase (and cosynthase)

D-uroporphyrinogen decarboxylase

Question 1

Synthesis of Heme

Answer 1

• Important in RBC, hemoglobin, myoglobin, and cytochromes

* Porphyrins are synthesized from glycine and succinyl CoA (rate determining step)** Required B6*

Question 2

Genetic or environmental defects in enzymes lead to _______.

Answer 2

• Porphyrias, such as lead or agent orange poisoning, photosensitifity (Dracula)
• ALA dehydratase dectefcs - lead poisoning
• Porphobilinogen deaminase defects - acute intermittent porphyria, hepatic, liver effected
• Uroporphyrinogen III synthase defects - congenital erythropoetic prophyria, RBC effected

Question 3

Heme breakdown

Answer 3

• Heme degradation products (biliverdin and bilirubin) responsible for the color of bruises
• RES enzymes begin this process to convert heme to these
• 2 sugars on bilirubin, secreted on bile, goes to the gut, microorganisms modify this, from there convert to urobilinagin

Question 4

Two fates of urobilinagin

Answer 4

1. Reabsorb in blood, goes to kidney, urinated out, oxidized to urobilin, yellow color
2. Rest enzymatically changed to stercobilinogen, oxidized to stercobilin, brownness of feces

Question 5

Bilirubin

Answer 5

• reddish color, hydrophobic, carried in the blood by albumin
• indirect billirubin, carried to liver where it is modified
• Can cause severe brain damage if to much build up

Question 6

Sphingosine

Answer 6

• Precursor to membrane lipids

* Derived from Serine*

Question 7

Histamine is derived from?

Answer 7

•Histidine*

Question 8

Thyroxine is derived from?

Answer 8

•Thyrosine*

Question 9

Epinephrine is derived from?

Answer 9

•Thyrosine*

Question 10

Serotonin is derived from?

Answer 10

•Tryptophan*

Question 11

Nicotinamide (unit of NAD+) is derived from?

Answer 11

•Tryptophan*

Question 12

Nitric Oxide is generated from?

Answer 12

• Arginine

* Relaxes smooth muscle, made in endothelium, pass through membranes very rapidly

Question 13

One of the mechanisms of destruction of NO is?

Answer 13

• macrophages

* NO combined with superoxide to make peroxinitrit (ONOO), very destructive, killa!

Question 14

NO is used as what?

Answer 14

• Nervous tissue produces NO
• Signal molecule/neurotransmission
• Excitotoxicity, excessive stimulation of one side of the brain, to much makes pathogenic

Question 15

ENOS, INOS, and NNOS stand for?

Answer 15

• ENOS = endothelium NO synthase
• INOS = Ineducable NO synthase in macrophages
• NNOS = Nervous tissue

Question 16

Glutathione system

Answer 16

• Serves as an antioxidant, reacting with hydrogen peroxide and organic peroxides
• Cyto protection, enzyme that used glutathione to get rid of peroxide has specific chemical call selenium