Lecture 34 - Amino Acid Metabolism II

Question 1

Heme synthesis involves the reaction of glycine and _________.

Answer 1

succinyl-CoA

Question 2

The production of heme from succinyl CoA and glycine begins with the rate determining step. What enzyme controls this step?

Answer 2

delta-aminolevulinate synthase

Question 3

delta-aminolevulinate synthase controls heme synthesis, and requires what co-factor? A. succinyl-CoA B. Vitamin B6 C. Vitamin B3 D. Glycine

Answer 3

B. Vitamin B6

Question 4

The production of heme requires a cyclic ring structure, that is linearized with other porphobilinogen rings. What enzyme catalyzes this reaction? A. ALA dehydratase B. porphobilinogen deaminase C. uroporphyrinogen III synthase D. Uroporphorynogen decarboxylase

Answer 4

B. porphobilinogen deaminase (the removal of an NH3 allows for the formation of a linear terapyrrole)

Question 5

Production of the initial porphyrinogen ring is catalyzed by what enzyme? A. uroporphyrinogen III synthase B. porphobilinogen deaminase C. ALA dehydratase D. Uroporphorynogen decarboxylase

Answer 5

A. uroporphyrinogen III synthase

Question 6

A patient presents with neuropsychiatric symptoms, as well as fluorescent crystals on the skin. When exposed to UV radiation, the patient complains of severe pain. You believe they are suffering from a heme synthesis disorder. What condition is described here, and what enzyme is deficient?

Answer 6

Disease: acute intermittent porphyria Enzyme: porphobilinogen deaminase; unable to produce linear tetrapyrrole

Question 7

Congenital erythropoetic prophyria is an enzyme deficiency that results in erythrocyte damage. UV radiation may result in the formation of painful vesicles and that rupture. What enzyme is deficient?

Answer 7

uroporphyrinogen III synthase

Question 8

The breakdown of heme begins when heme is converted to _________. A. Biliverdin B. Bilirubin diglucuronide C. Bilirubin

Answer 8

A. biliverdin

Question 9

The breakdown of biliverdin produces ___________. A. Additional biliverdin B. Bilirubin diglucuronide C. Bilirubin

Answer 9

C. bilirubin

Question 10

Bilirubin is produced in the ____ to form bilirubin diglucuronide. A. bloodstream B. intestines C. liver

Answer 10

C. liver

Question 11

The liver changes bilirubin to bilirubin diglucuronide using what enzyme?

Answer 11

UDP-glucuronide transferase

Question 12

Outline the breakdown of heme, including where breakdown occurs, the products, and how they are excreted.

Answer 12

Question 13

Some premature infants require “bili-lights” after birth. For what reason is this treatment used?

Answer 13

Bilirubin is removed in utero from the fetus by the placenta. After birth, the child’s liver begins the processing of bilirubin. As it takes some time for this to occur, free bilirubin may lead to jaundice. Bili lights stimulate the removal of unconjugated bilirubin by stimulating the release of water soluble bilirubin.

Question 14

What molcules are serine deriviatives?

Answer 14

Sphingosine (contains -OH in side chain)

Question 15

What molecule is histidine derived?

Answer 15

Histamine

Question 16

What molecules are tyrosine derivatives?

Answer 16

Thyroxine and epinephrine (contain aromatic rings with -OH group)

Question 17

What molecules are tryptophan derivatives?

Answer 17

Serotonin

Nicotinamide

Question 18

Nitric oxide is derived from what amino acid?

Answer 18

arginine

Question 19

Nitric oxide synthase is the enzyme for nitric oxide synthesis. What cofactor is required?

Answer 19

BH4

Question 20

This produces Nitric Oxide as a neurotransmitter.

Answer 20

n-NOS

Question 21

This produces Nitric Oxide as part of the macrophage’s role in free-radical mediated pathogen destruction.

Answer 21

i-NOS

Question 22

This produces Nitric Oxide as a vasodilator

Answer 22

e-NOS (endothelial NO synthase)

Question 23

PKU produces ketone bodies that result in neurological disfunction. Which PKU type results form enzyme deficiency?

Answer 23

Type I

Question 24

The glutathione system acts to protect the body from free radicals. What ion is used as the actual anti-oxidant?

Answer 24

Selenium

Question 25

PKU produces ketone bodies that may result in neurological disfunction. Type II sees what defiency in the chemical process?

Answer 25

BH4