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SFM Exam 2 > 12: Protein And AA Metabolism > Flashcards

12: Protein And AA Metabolism Flashcards

1
Q

Three things that supply the AA pool

A
  1. Protein turnover
  2. Digested food
  3. De novo synthesis of non-essential AAs
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2
Q

Three things that deplete the AA pool

A
  1. Body protein production
  2. Synthesis of nitrogenous compounds
  3. Degradation
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3
Q

9 essential AAs

A

H, V
MILK
WTF

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4
Q

Six conditionally essential AAs

A

RPG

CQY

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5
Q

5 non-essential AAs

A

DANSE

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6
Q

Major source of N in the body

A

Dietary protein

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7
Q

Four ways the body excretes N

A
  1. Ammonia
  2. Creatinine
  3. Uric acid
  4. Urobilinogen
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8
Q

In what organ does AA metabolism take place?

A

Liver

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9
Q

What two things form from ketogenic AAs and what two things form from glucogenic AAs?

A

Ketogenic -> acetyl CoA, acetoacetate

Glucogenic -> pyruvate, TCA cycle intermediates

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10
Q

Ketogenic AAs are precursors for what three things?

A

A-keto acids, ketone bodies, FAs

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11
Q

Glucogenic AAs are precursors for what process?

A

Gluconeogenesis

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12
Q

Two ketogenic AAs

A

Leu, Lys

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13
Q

5 AAs that are both ketogenic and glucogenic

A

WIFY T

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14
Q

Release of trypsinogen and chymotrypsinogen

A

Are released into SI lumen as inactive zymogens

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15
Q

What activates trypsinogen?

A

Enteropeptidase (an enterokinase embedded in the intestinal mucosa)

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16
Q

What two things does trypsin activate

A

Chymotrypsinogen + other trypsinogen molecules

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17
Q

Three steps in AA Degradation

A
  1. Aminotransferase
  2. Glutamate dehydrogenase
  3. Urea cycle
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18
Q

Other term for aminotransferase

A

Transaminase

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19
Q

What occurs during a transamination reaction?

A

Amino group of AA is transferred to an a-ketoacid

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20
Q

Coupled reactions of AAs and keto acids

A

All AAs have a conjugate keto-acid; like acid-base reactions

AA + keto acid -> a different AA + keto acid

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21
Q

Required coenzyme for aminotransferase reactions

A

PLP (pyridoxyl-5’-phosphate) (derived from B6)

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22
Q

Two examples of aminotransferases used as markers in medicine

A

Alanine transaminase, aspartate transaminase

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23
Q

What four AAs form glutamate -> which then forms a-ketoglutarate

A

Gln, His, Arg, Pro

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24
Q

Byproduct of glutamine glutamate reactions

A

NH4+

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25
What two enzymes do the glutamine glutamate reactions
Glutamate dehydrogenase, glutamine synthase
26
What cofactor is required in the methionine pathway?
PLP
27
Three branched chain AAs
Valine, Leucine, Isoleucine
28
What does phenylalanine hydroxylase do?
Turns Phe into Tyr
29
How is ammonia removed from the brain vs other tissues
Removed from brain: as Glu or Gln | Removed from other tissues: as Glu
30
How is urea generated?
In AA metabolism by deamination mechanisms
31
Goal of urea cycle
Produce urea from ammonia
32
What can defects in any of the six urea cycle enzymes cause?
Hyperammonemia
33
Example of a urea cycle enzyme
NAG synthase
34
Where does the urea cycle occur?
Liver mostly, kidneys a little
35
What does ammonia toxicity mostly affect
Brain and CNS
36
Toxic agent in ammonia toxicity and why
NH3 - it can penetrate membranes
37
Four things formed from tryptophan
Serotonin -> melatonin | Niacin -> NADH/NADPH
38
What do serine and glutamate form?
Serine: Ach Glutamate: GABA
39
Four things formed by tyrosine
1. Thyroid hormones 2. Dopamine -> norep/epi 3. Melanin
40
Thyroglobulin
120 Tyr residues with iodine stuck on them, helps form T3 and T4
41
T3 vs T4
T4: 2 diionated Tyr T3: 1 monoiodonated + 1 diiodinated Tyr
42
Inborn Errors of Metabolism (IEMs)
Conditions associated with dysfunctional metabolism of AAs/thier derivatives
43
How many core IEMs are screened, and how many does Missouri screen for?
34 core conditions; 59 screened in MO
44
Two things Hartnup disease and Cystinuria have in common
1. Autosomal recessive | 2. Associated with defects in AA transporters
45
cause of Hartnup disease
Defective transport of non-polar/neutral AAs (ex: Tryptophan)
46
What does Hartnup disease cause?
Trp deficiency
47
Clinical associations of Hartnup disease
Elevated Trp in urine, failure to thrive, nystagmus, tremor, intermittent ataxia, photosensitivity
48
Cause of cystinuria
Defective transport of dimerize cystine and dibasic AAs
49
Four dibasic AAs
COAL: cysteine, ornithine, arginine, lysine
50
Clinical associations of cystinuria
Formation of cystine crystals in kidney, renal colic
51
What AA is homocysteine most like?
Methionine
52
Homocystinuria cause
Deficiency in methionine pathway, folate deficiency, or PLP deficiency
53
Four organ systems affected by hyperhomocysteinemia
Eyes, skeletal, CNS, vascular
54
Treatment for hyperhomocysteinemia
Vitamin supplements can sometimes normalize homocysteine levels
55
What causes maple syrup urine disease
Defective BCKD (branched-chain a-keto acid dehydrogenase complex), which causes branched-chain keto-aciduria
56
Clinical associations of maple syrup urine disease
Maple syrup urine smell, toxicity in brain (due to branched chain AAs in brain)
57
Treatment of maple syrup urine disease
Synthetic diet limiting BCAAs
58
What was the first IEM to be included in newborn screenings?
Phenylketonuria
59
What causes phenylketonuria
Phenylalanine hydroxylase deficiency: cant form Tyr from Phe
60
Clinical association of phenylketonuria
Blocked AA transport in the brain, impaired brain function
61
Treatment of phenylketonuria
Limit Phe + use formula containing Tyr
62
Secondary PKU causes what?
Tetrahydrobiopterin deficiency (a cofactor of phenylalanine hydroxylase)
63
What causes albinism?
Defects in tyrosinase -> conversion of tyrosine to melanin is blocked
64
What is special about orotic aciduria
It is an X-linked disease of the urea cycle
65
What enzyme is defective in orotic aciduria
Ornithine transcarbamoylase

SFM Exam 2 (19 decks)

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