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Amino Acid Metabolism Flashcards

1
Q

ammonia toxicity is seen in (2)

A

liver failure

inborn errors of metabolism

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2
Q

Effects of ammonia intoxicatio in inborn errors of metabolism n are primarily

A

on the nervous system, leading to dizziness, coma, convulsions

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3
Q

ammonia toxicity in liver failure is tx with

A

dietary restriction

eat as little protein as possible, only essential aa

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4
Q

Symptoms of Ammonia Toxicity include:

A

Irritability

V omiting

Lethargy & confusion

Respiratory distress

Migraines

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5
Q

POSSIBLE MECHANISMS FOR AMMONIA TOXICITY

Brain glutamate dehydrogenase forms glutamate from _____

A

α-ketoglutarate and NH3

this lower pools of α-ketoglutarate

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6
Q

effect of lowered pool of α-ketoglutarate after it is converted with nh3 to glutamate

A

flux through tca cycle is reduced

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7
Q

POSSIBLE MECHANISMS FOR AMMONIA TOXICITY

Increased glutamate leads to increased ______ from the excess NH

A

inc glutamine

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8
Q

POSSIBLE MECHANISMS FOR AMMONIA TOXICITY

. Increased glutamate leads to increased glutamine from the excess NH3 —-> effect

A

brain pools of glutamate decrease (affecting NT glutamate levels and gaba)

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9
Q

POSSIBLE MECHANISMS FOR AMMONIA TOXICITY

Glutamine leaves brain neurons in exchange for ____

A

tryptophan.

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10
Q

POSSIBLE MECHANISMS FOR AMMONIA TOXICITY

Glutamine leaves brain neurons in exchange for tryptophan —->

A

Trp is converted to serotonin —> high serotonin thought to be cause of coma in liver failure

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11
Q

____ is thought to be an important factor in coma associated with liver failure.

A

High serotonin

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12
Q

possible cause of ammonia toxicity in the brain

A

Uncontrolled changes in the levels of 3 neurotransmitters (glutamate, GABA and serotonin) in the brain.

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13
Q

The degradation of the AA carbon skeletons involves the removal of ___ and disposal of ___

A
  1. removal of nitrogen
  2. disposal of carbon skeletons
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14
Q

Ketogenic- amino acids are degraded to either

A

acetyl coenzyme A or acetoacetyl CoA

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15
Q

_ Ketogenic_- amino acids are degraded to either acetyl coenzyme A or acetoacetyl CoA, which give rise to ____

A

ketone bodies

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16
Q

Glucogenic- amino acids are degraded to ___

A

pyruvate or citric acid cycle intermediates,

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17
Q

Glucogenic- amino acids are degraded to pyruvate or citric acid cycle intermediates, which can give rise to ____ via formation of ____

A

glucose via formation of phosphoenolpyruvate.

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18
Q

_____ amino acids can provide an excellent source of glucose after glycogen stores are gone.

A

Glucogenic

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19
Q

can the ** carbons in ketones and acetyl-CoA** can or cannot be converted into glucose,

A

cannot be converted into glucose

can only be converted into FA

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20
Q
  • Some amino acids can be degraded into multiple intermediates which can be classified as
A

ketogenic and glucogenic.
[I, F, Y, W, T]

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21
Q

amino acids that are exlcusively ketogenic

A

leucine
lysine

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22
Q

five amino acids are both ketogenic and glucogenic:

A

isoleucine
phenylalanine
tryptophan
tyrosine
threonine

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23
Q

amino acid degradation

Alanine is converted to pyruvate by transamination with α-ketoglutarate by

A

alanine transaminase

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24
Q

Serine is converted to pyruvate by ____ by serine dehydratase.

A

direct deaminatio

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25
Cysteine can be converted to pyruvate by a \_\_\_
desulfhydrase.
26
Glycine is converted by\_\_\_\_ to serine
serine hydroxymethyltransferase
27
Glycine is converted by serine hydroxymethyltransferase to \_\_\_\_\_
serine
28
Glycine is converted by serine hydroxymethyltransferase to serine, which is then converted to \_\_\_\_ ## Footnote
pyrvuate
29
how to get from glycine to pyrvuate?
glyceine ---\> serine ---\> pyruvate
30
Glycine is converted by serine hydroxymethyltransferase to serine was is taken up? what is removed?
31
how can glyceine be broken down into Co2 and free ammonia?
Glycine Cleavage Enzyme (glycine synthase, run in reverse)
32
glycine---\> co2 and NH4 what is given off
33
glycine---\> via GLYCINE CLEAVAGE ENZYME
CO2 + NH4
34
how to get pyvuravate from threonine?
threonine --\> glycine ---\> serine ---\> pyvruvate
35
threonine --\> glycine via what enzyme?
aminoacetone
36
what is generated with aminoacetone --\> glycine?
acetyl coa
37
**Aspartate** is converted by transamination with α-ketoglutarate to \_\_\_\_\_\_
oxaloacetate
38
why does asparate need to be in the liver?
to feed ammonia groups into the urea cycle
39
what is asparate converted to? what is it a marker of?
Aspartate is converted by transamination with α-ketoglutarate to **oxaloacetate** marker of liver failure
40
HOW TO GET FROM ASPARIAGINE TO OXALOACETATE?
ASPARAGINE ---\> ASPARATE ---\> OXALOACETATE
41
ASPARAGINE --\> ASPARTATE BY?
ASPARAGINASE
42
Glutamine- converted to glutamate by \_\_\_.
glutaminase
43
Histidine- converted to ____ by a series of reaction that include **transfer of its formino group** to **tetrahydrofolate.**
glutamate
44
HOW IS HISTIDINE CONVERTED TO GLUTAMATE?
HISITIDINE --\> UROCANIC ACID --\> 4-IMIDAZOLONE-5-ACID ---\> N-FORMINOGLUTAMATE **(TRANSFER OF FORMINO GROUP TO TETRAHYDROFOLATE) --\> GLUTAMATE**
45
HOW IS ARIGINE CONVERTED TO GLUTAMATE?
ARIGINE --\> ORNITHINE --\> GLUTAMATE SEMIALDHEYDE --\> GLUTAMATE
46
HOW IS PROLINE CONVERTED TO GLUTAMATE?
PROLINE --\> GLUTAMATE SEMIALDEHYDE --\> GLUTAMATE
47
When we synthesize arginine, we make ornithine and then
run it through the urea cycle.
48
You can synthesize arginine, but during growth or positive nitrogen balance you need extra, since
in the liver it constantly be degraded to ornithine and urea.
49
Valine, leucine, and isoleucine each are converted to their corresponding α-keto acid by the actions of
transaminases.
50
\_\_\_\_ (3) each are converted to their corresponding α-keto acid by the actions of transaminases.
Valine, leucine, and isoleucine (branched AA)
51
BCAT (branched chain AA transaminase) deficiency in mice has been shown to cause
increased insulin sensitivity, increased protein turnover, increased serum leucine levels, decreased fat and body weight, and increased energy expenditure. can't converted valine, leuicen, isoleucine to corresponding a-ketoacid
52
what catalyzes the oxidative decarboxylation of valine, leuiceine, isoleucine
a common branched-chain keto acid dehydrogenase
53
what does branched-chain keto acid dehydrogenase use as cofactors?
lipoamide, thiamine pyrophospate, FAD and NAD.
54
another name for branched chain ketoaciduria?
maple syrup urine disease
55
what causes maple syrup urine disease
defect in branched-chain keto acid dehydrogenase.
56
MAPLE SYRUP URINE DISEASE --\> characteristic odor is caused by
build up of keto acids due to the defect in branch chaoin keto acid dehydrogenase
57
tx of maple syrup urine disease
restricted diet, **avoiding isoleucine, leucine, valine** some pts respond to **thiamine**
58
Methionine, isoleucine and valine are degraded by different pathways to form\_\_\_ via methylmalonyl CoA.
succinyl CoA
59
Methionine, isoleucine and valine are degraded by different pathways to form succinyl CoA via \_\_\_
methylmalonyl CoA.
60
\_\_\_ (3) are degraded by different pathways to form succinyl CoA via methylmalonyl CoA.
Methionine, isoleucine and valine
61
\_\_\_\_ is formed by the hydroxylation of phenylalanine
Tyrosine
62
Tyrosine is formed by the hydroxylation of phenylalanine enymze? cofactor?
Enzyme: Phenylalanine hydroxylase Cofactor Tetrahydrobiopteri
63
how can low NADH affect tyrosine levels
Tetrahydrobiopterin wouldnt be replenished, which is a cofactor in the pheynlaline --\> tyrosine reaction Tetrahydrobiopterin is regenerated by dihydrobiopterin reductase which uses nadh as a reductant
64
Phenylketonuria is a genetic disorder associated with the inability to catalyze the
hydroxylation of phenylalanine the subsequent accumulation of toxic **derivatives of phenylalanine such as phenylpyruvate.**
65
PKU TX
phenylalanine restricted diet until the age of at least 16y/o.
66
GENE MUTATIONS CAUSING A REDUCTION IN THE ENZYME ____ CAN CAUSE PKU
Phenylalanine hydroxylase
67
Atypical PKU- caused by a defect in the
dihydrobiopterin reductase
68
DIFFERENCE IN TX OF ATYPICAL PKU VS. PKU
NO TX FOR PKU
69
WHAT IS MATERNAL PKU?
HIGH PHENYLALINE LEVELS IN MOTHER WITH PKU ---\> MENTAL RETARDATION IN FETUS
70
MECHANISM OF CONVERSION OF PHENYLALINE TO TYROSINE?
BH4 IS A COFACTOR NADH IS NEEDED BY BH2 REDUCTASE TO REVERT IT BACK O2 IN, H20 OUT
71
Homogentisate is converted to \_\_\_
4-maleylacetate
72
**Homogentisate is converted to 4-maleylacetate** Enzyme: Homogentisate oxidase Defect: \_\_\_\_
Alkaptonuria
73
Alkaptonuria IS CAUSED BY
DEFECTIVE **HOMOGENTISIC ACID 1,2-DIOXYGENASE** NEEDED FOR HOMOGENTISTIC ACID--\>4-Maleyl-acteoacetic acid
74
Homogentisate ---\> 4-maleylacetate Enzyme: \_\_\_\_ Defect: Alkaptonuria
Homogentisate oxidase
75
tryptophan is an important precursor of the neurotransmitter serotonin and can contribute to the pool of
NIACIN
76
DEFICIENCY IN WHAT AA COULD CAUSE PELLAGRA (NIACIN DEF.)
TRPYTOPHAN
77
The degradation of lysine is complex, but eventually leads to the production of \_\_\_\_
acetyl CoA,
78
\_\_\_ amino acids are essential and must be acquired from the diet.
9
79
HOW IS ALANINE FORMED?
A TRANSMINATION RXN FROM PYRUVATE
80
HOW IS ASPARATE FORMED?
from oxaloacetate by a transamination reaction.
81
three common methods for adding NH3 groups to molecules:
1) transamination 2) Asp–\>Fumarate 3) Gln –\>Glu.
82
GLUTAMATE FORMATION? (2)
1. reductive amination of a **α-ketoglutarate** by **glutamate dehydrogenase.** 2. transamination of α-ketoglutarate by almost any other amino acid.
83
HOW IS GLUTAMIEN FORMED?
formed by the amidation of glutamate.
84
Proline may be formed in two steps from \_\_\_
glutamate.
85
Serine is synthesized in three steps from
3-phosphoglycerate, an intermediate in glycolysis.
86
Glycine can be made from \_\_\_
serine
87
Glycine can be made from serine in a reversible reaction by
serine hydroxymethyltransferase
88
Cysteine may be synthesized from
serine and methionine.
89
cysteine is only nonessential if ___ is provided in the diet.
methionine
90
Tyrosine is an essential amino acid in
people who dont get phenylaline in their diet people with pku
91

MCP (16 decks)

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