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MBOD Week 13 > Amino Acid Degradation > Flashcards

Amino Acid Degradation Flashcards

1
Q

What is the fate of amino acids in the fed and fasting states?

A

Fed State:
Amino Acids Used for synthetic processes

Fasting State:
Proteins are degraded (in muscle mostly) so Amino Acids can be:
- Used for Energy
- Used for Gluconeogenesis
- Modified to maintain appropriate levels of Amino acids

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2
Q

What insulin counterregulatory hormones are released during fasting?

A
  1. Glucagon (Mobilizes Fuels)
  2. Norepinephrine (stress)
  3. Epinephrine (stress)
  4. CORTISOL (long term effect on muscles)
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3
Q

What does Cortisol do?

A

Provides for changing requirements over the long term - (Tells muscles what to do because Glucagon can’t)

Stimulates:

  1. Mobilization of Amino Acids from Muscle Protein
  2. Gluconeogenesis to produce glucose for glycogen synthesis
  3. Release of Fatty Acids from Adipose
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4
Q

T or F: All 20 amino acids can be broken down into pyruvate, acetyl CoA or a citric acid cycle intermediate.

A

TRUE, these are used to generate energy, glucose, or storage molecules (Fatty Acids)

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5
Q

What does Cortisol do in the muscle?

A
  • Signals protein breakdown
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6
Q 
Categorize the following based on their usage:
Alanine
Glutamine
Leucine
Isoleucine
Valine
A

Nitrogen Carriers In Bloode:
Alanine
GLUTAMINE (Major Carrier)

Energy:
Branched Chain Amino Acids (BCAAs)
Leucine
Isoleucine
Valine
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7
Q

What explains the fact that the average protein contains very little Alanine and Glutamine, yet they are a large part of Amino Acids in blood?

A
  • While Glutamine and Alanine usually only make up a small portion of any given protein, they are the MAJOR TRANSPORTER OF AMINO ACIDS in the BLOOD.
  • Other amino acids like BCAAs are converted to these so they can move through the blood.
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8
Q

What explains the fact that the average amount of BCAAs (leu, Iso, Val) in the blood is substantially less than what is found in a typical protein?

A
  • BCAAs are used as energy (TCA) or are converted to Alanine and Glutamine
  • This leaves very little leftover BCAAs to move in the blood
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9
Q

What 3 things can all amino acids be broken down into?

A
  1. Pyruvate
  2. Acetyl-CoA
  3. Citric Acid Cycle Intermediate
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10
Q

What amino acids are a major fuel source in skeletal muscle and peripheral tissue during fasting?

A
  • BCAAs
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11
Q

What preliminary step must happen before amino acids can be used for energy or stored as fatty acids?
- how is this done?

A

alpha-amino group (nitrogen) must be removed

2 ways:

  1. TRANSamination
  2. DEamination
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12
Q

What is the difference between Transanimation and Deamination?

A

Transamination:
Moves Amino group between KETO acids
-usually FUNNELS to GLUTAMATE

Deamination:
Removes the ammonia

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13
Q

What is the purpose of transamination reactions?

A
  1. To get the right amino acids in the right place (aka FUNNELING AMINO ACIDS)
  2. To make sure you have appropriate amounts of all amino acids
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14
Q

What are enzymes called that catalyze transamination reactions?

  • cofactor
  • reversibility of reactions
  • Times of high activity
A

Transaminases
Aminotransferases

PLP (pyridoxal phosphate) coefactor derived from B6 (ALL TRANSAMINATION REACTIONS)

  • These reactions are easily reversed
  • USED IN BOTH SYNTHESIS OF AA AND DEGRADATION
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15
Q

T or F: all amino acids can undergo transamination reactions.

A

False, Lysine and Threonine are the only two that can’t

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16
Q

What amino acid is most commonly involved in transamination reactions?

A

glutamate and alpha-ketoglutarate

17
Q

What two amino transferases are used as diagnostic markers?

  • location
  • indications high of markers
A

ALT (alanine aminotransferase)

  • Elevated levels in serum means LIVER damage causing abnormal levels into the bloodstream
  • Predominant location = liver

AST (aspartate aminotransferase)

  • Elevated levels mean damage to liver or CARDIAC OR SKELETAL MUSCLE.
  • Predominant location = liver, cardiac, and sketetal mm.
18
Q

Where can the transamination products of Isoleucine, Leucine, and valine enter the TCA cycle?

A

Isoleucine - Acetyl CoA, Succinyl CoA
Leucine - Acetyl CoA
Valine - Succinyl CoA

19
Q

Succinyl-CoA and Acetyl-CoA from BCAAs is used for what two processes?

A
  1. Energy via the TCA cycle
  2. Glutamine via alpha-ketoglutarate
    - some is also used to make alanine
20
Q

Maple Syrup Urine Disease (MSUD) (aka Branched Chain Ketoaciduria)

  • Cause
  • Symptoms
  • Treatment
A
  • Disorder of alpha-Keto Acid Dehydrogenase complex (autosomal recessive)
  • Sweet smelling urine, progressive neurologic damage, seizure etc.

Treament:
- Lifelong restriction of dietary Valine, Leucine, Isoleucine

21
Q

What enzyme COMPLEX is responsible for turning alpha-Keto acids to Acetyl CoA or Propionyl CoA —> —> Succinyl CoA

A

alpha-Keto Acid Dehydrogenase

22
Q

What amino acids become high in the blood with Maple Syrup Urine Disease?

A

High BCAA in the blood because they can’t be used for energy via their defective alpha-Keto Acid Dehydrogenase Complex

23
Q

What is generated in the conversion of BCAAs to acetyl CoA or Succinyl CoA?

A
  • NADH and FADH2

* *Note: Acetyl CoA and Succinyl CoA can also be ran through the cycle to get Glutamine

24
Q

WHAT FIVE AMINO ACIDS CAN YIELD ALANINE WHEN DEGRADED?

- why would such degradation take place

A
  1. Cysteine
  2. Glycine
  3. Serine
  4. Threonine (via pyruvate)
  5. Tryptophan
  • This would occur when there is a shortage of alanine or energy
25
Q

WHAT FOUR AMINO ACIDS CAN YIELD GLUTAMATE?

- reason for this degradation

A
  1. Arginine
  2. Proline
  3. Histidine (via glutamate)
  4. Glutamate
  • This would occur when there is low energy in the cell or lack of glutamate
26
Q

What happens to alanine in the fasting state?

- is only alanine degraded?

A

It is shunted from the muscle into blood then liver for gluconeogenesis

  • No alanine is not the only protein degraded BCAAs aminate pyruvate to get Alanine
27
Q

What amino acids are ketogenic only and cannot make glucose?

  • what is ketogenic
  • synthetic uses
A
  • Leucine
  • Lysine
  • Ketogenic means any amino acid that can become Acetyl CoA
  • Used for Fatty acid and Ketone Body Synth
28
Q

What amino acids are glucogenic?

- glucogenic and ketogenic?

A

The other 18
*Note: all of these can form pyruvate OR a TCA cylcle intermediate

Ketogenic + Glucogenic

  1. Isoleucine
  2. Threonine
  3. All Aromatics (tyr, phe, trp)
29
Q

T or F: ALL glucogenic can be used in gluconeogenesis

A

True

30
Q

What are the three purposes of transporting glutamine to the kidneys?

A
  1. TCA cycle - (through alpha-KG)
  2. Gluconeogeneis - (through alpha-KG)
  3. Convert Alanine to Serine
31
Q

Which amino acid in the blood is a major source for gluconeogenesis?

A

Alanine (transaminated to pyruvate)

32
Q

Which amino acid is the major carrier for nitrogen in the blood?

A

Glutamine

33
Q

T or F: amino acids are also used for energ in the fed state.

A

True

34
Q

What happens to those amino acids that are ketogenic during gluconeogenesis?

A
  • Converted to Acetyl-CoA —-> Fatty Acids or Ketone Bodies
35
Q

Why do BCAAs (Iso, Leu, Val) build up in maple syrup urine disease?

A
  • alpha-ketoacid dehydrogenase doesn’t work
  • These amino acids build up because they can’t take the next step to becoming glucogenic and ketogenic intermediates like they usually do

MBOD Week 13 (7 decks)

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