Amino Acid Metabolism II

Question 1

Describe the 3 pathways that are used to synthesize amino acids and the pathways that they are related to

Answer 1

3-phosphoglycerate, phosphoenolpyruvate and pyruvate from glycolysis

alpha-ketoglutarate and OAA from the TCA cycle

Ribose-5-phosphate, erythrose-5-phosphate from the pentose phosphate pathway

Question 2

What are the 3 transamination reactions that occur in amino acid syntheses

Answer 2

1. pyruvate/alanine by SGPT
2. OAA/Aspartate by SGOT
3. alpha ketoglutarate/glutamate exchange by Glutamate dehydrogenase

Question 3

What are the fates of aspartate and what enzymes catalyzes these reactions?

Answer 3

1. Asparagine synthetase changes the molecule into asparagine
2. In other organisms, Aspartate can be turned into lysine, methionine and threonine

Question 4

Describe the fate of glutamate?

Answer 4

Glutamine synthetase forms glutamine

Question 5

What is the difference between synthetases and synthases?

Answer 5

Synthetases use ATP and synthases do not

Question 6

Describe the regulation of glutamine synthesis

include what protein is involved

Answer 6

Adenylation (AMP addition) of the glutamine synthetase inactivates the enzyme

PII is a protein that binds to the adenylyl transferase, which causes adenylation of the enzyme (inactivation)

If a UMP is aded to the PII protein via uridylylation, and that binds to the adenylyl transferase, then the enzyme is deacetylated and the enzyme is activated

Question 7

Why is it important that the cells are able to make glutamine from glutamate?

Answer 7

So that the excess NH4+ can be transported to the liver so that it can go through the urea cycle

Question 8

What are the amino acids that can be formed from glutamate?

Answer 8

Glutamine, Proline, and Arginine

Question 9

What are the amino acid derivatives of 3-phosphoglycerate?

Answer 9

1. three reactions get to serine
2. vitamins B6 and B12 help to remove the side chains from serine to make glycine
3. serine can be converted through cysteine via a homocysteine

Question 10

What is tyrosine a catabolic intermediate of?

Answer 10

Phenylalanine

Question 11

Where are aromatic amino acids derived from? And which intermediates from this pathway make 
Histidine 
Tryptophan 
Phenylalanine 
Tyrosine

Answer 11

Aromatic amino acids come from the pentose phosphate pathway

Histidine comes from ribose-5-phosphate

tryptophan, phenylalanine and tyrosine come from Erythrose 4 phosphate combining with phosphoenolpyruvate to make choorismate

Question 12

List and describe the amino acids that are synthesized from pyruvate?

Answer 12

Valine, Leucine, and Isoleucine

All have complex syntheses, exist to be incorporated into proteins, and are regulated by feedback inhibition

Question 13

List the uses of amino acids

PAN

Answer 13

All Planning Parents Perform Active Sex Regularly—Now Pregnant

Activated Carriers 
Polypeptides 
Precursors 
Pigments 
Antioxidants 
Signaling Molecules 
Regulatory molecules 
Neurotransmitters 
Polyamines

Question 14

What are the two central amino acids?

Answer 14

Glycine and Serine

Question 15

Describe Heme

Answer 15

Acetate is converted to succinyl CoA prior to assembly

used for O2 transport

Heme is the main source of dietary iron

Question 16

Describe the deficiencies in Heme synthesis

1. What happens if there is a deficiency in a liver enzyme?

2/ A non-liver enzyme?

Answer 16

Porphyrias

1. Sx related to pain and cardiac dysfunction
2. non-liver; light sensitivity and altered skin pigmentation

Question 17

Describe aliphatic molecules. What happens if you change the ring?

Answer 17

They absorb light via the pi-orbitals.

if you change the ring, you change the wavelength that is absorbed and changes the color transmitted (our eyes only see the transmitted)

Question 18

What are the molecules that are derived from glutamate?

Answer 18

Glutathione-antioxidant
Polyamines-stabilize DNA
GABA- inhibitory neurotransmitter

Question 19

List and describe the two arginine derived molecules

Answer 19

1. NO: free radical that is from NOS; tied to G-protein signal cascade; nitroglycerin releases 3 equivalents of NO
2. creatine phosphate: liver releases into the bloodstream; hydrolysis of phosphate from creatine releases same amount of energy as ATP
3. uses SAM (methyl donor) a TON

Question 20

What are the histidine derived molecules?

Answer 20

Histamine- secretion of HCl and pepsin in the stomach, vasodilation at the site of allergic reaction, neurotransmission

Question 21

What kind of inhibition do antihistamines use?

Answer 21

Competitive inhibition

Question 22

What are the tryptophan derived molecules?

Answer 22

serotonin; dictate insulin release from the pancreas, vasoconstriction and blood pressure regulator, intestinal contraction, NOS activation, and a precursor for melatonin

Question 23

Describe the tyrosine-derived molecules

Answer 23

Catecholamines:
epinephrine (stress hormone) that causes vascular constriction, increase in blood pressure, and ceases inflammation

dopamine: increased leads to drug addiction and parkinson’s, decreased levels in parkinson’s and ADHD

Question 24

Describe dark hair color

Answer 24

Eumelanins> phemolanins

Question 25

Describe light hair color

Answer 25

Pheomelanins> eumelanins

Question 26

What is albinism caused by?

Answer 26

A deficiency in tyrosinase