Amino acid metabolism Flashcards

1
Q
A

Nitrogen pool

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2
Q
A

Tissue protein

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3
Q
A

Urea cycle

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4
Q

Transamination

A

Exchange of an amine group with a ketone group from another molecule

  • Catalysed by transaminases
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5
Q

What is the most frequent keto-acid involved in transamination?

A

Alpha-ketoglutaric acid

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6
Q

Give an example of a transamination reaction

A

Alanine + alpha-ketoglutaric acid → Pyruvic acid + Glutamic acid

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7
Q

Structure: Alanine

A
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8
Q

Structure: α-ketoglutarate/α-ketoglutaric acid

A
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9
Q

Structure: Pyruvic acid/Pyruvate

A
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10
Q

Structure: Glutamic acid

A
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11
Q

When is transamination seen?

A

During amino acid synthesis

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12
Q

What are the ‘collection’ and ‘receiving’ agents for nitrogen?

A
  • α-ketoglutarate
  • Glutamic acid
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13
Q

List some transaminases

A
  • ASAT=GOT
  • ALAT=GPT
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14
Q

Location of ASAT=GOT

A

In the cytosol/mitochondrion of:

  • Liver
  • Heart
  • Muscle
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15
Q

Location of ALAT=GPT

A

In the cytosol/mitochondrion of:

  • Liver
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16
Q

Title the figure

A

Ketoglutaric + Glutamic acid

Synthesis of amino acids and other nitrogen bases

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17
Q
A

Nitrogen bases

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18
Q
A

Transamination

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19
Q
A

Transamination

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20
Q
A

Amino acid

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21
Q
A

Ketoacid

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22
Q

Cysteine is synthesised from…

A
  • Methionine
  • Serine
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23
Q

Glycine is synthesised from…

A

Phosphoglyceric acid

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24
Q

Which amino acids are essential in the chicken?

A
  • Glycine
  • Arginine
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25
Q

Give the relevance of essential amino acids in ruminants

A

Ruminants have no essential amino acids

They are produced by rumen microbes

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26
Q

Oxidative deamination

A

Amino acid → Keto acid

  • Removal of amine functional group (NH3)
  • Amin functional group is replaced by the ketone group
27
Q

Oxidative deamination occurs primarily on…

A

Glutamic acid

28
Q

Glutamate dehydrogenase is allosterically controlled by…

A
  • ATP (Inhibitor)
  • ADP (Activator)
29
Q

Title the figure

A

Oxidative deamination

30
Q

Once keto acids have been formed, they can be used for…

A

Metabolism into CO2 + H2O

Via Citric acid cycle

31
Q

Amino acids converted into acetyl-CoA can be converted into…

A

Ketone bodies

32
Q

Title the figure

A

The fate of Amino acid carbon skeletons

33
Q

Amino acids producing pyruvate

A
  • Alanine
  • Glycine
  • Cysteine
  • Serine
34
Q

Amino acids producing acetyl-CoA

A
  • Isoleucine
  • Leucine
  • Tryptophan
35
Q

Amino acids producing oxaloacetate

A
  • Aspartic acid
  • Asparagine
36
Q

Amino acids producing fumarate

A
  • Tyrosine
  • Phenylalanine
  • Aspartic acid
37
Q

Amino acids producing succinyl-CoA

A
  • Isoleucine
  • Methionine
  • Threonine
  • Valine
38
Q
A

Acetoacetyl CoA

39
Q

Amino acids producing acetoacetyl-CoA

A
  • Leucine
  • Lysine
  • Phenylalanine
  • Tyrosine
40
Q

Amino acids producing α-ketoglutarate

A
  • Glutamic acid
  • Glutamine
  • Histidine
  • Proline
  • Arginine
41
Q

Ammonia is produced via…

A
  • Oxidative deamination
  • Degradation of biogenic amines
  • Absorption from the GI tract
42
Q

Ammonia is detoxified via…

A
  • Urea cycle
  • L-Glu synthesis
  • Gln + Asn synthesis
  • Kidney: Glutaminase activity
  • Purine synthesis: Uric acid (Birds)
43
Q

Which species lack the urea cycle?

A

Birds

They do not possess the arginase enzyme

44
Q

Portosystemic Shunt

A
  • Blood of portal vein enters the vena cava, not the liver
  • Ammonia toxicosis risk
  • Seen in Yorkshire terrier
45
Q

Title the figure

A

Glutamine synthesis + Degredation

46
Q

Reaction: Decarboxylation of amino acids

A

Amino acid → Amine

Amino acid decarboxylase

47
Q

Decarboxylation of Histidine

A

Histidine → Histamine

Histidine decarboxylase

48
Q

Decarboxylation of Tyrosine → Catecholamines

A

Tyrosine → DOPA → Catecholamines

Dihydroxyphenylalanine (DOPA) decarboxylase

49
Q

Decarboxylation of Tyrosine

A

Tyr → Tyramine

Tyrosine decarboxylase

50
Q

Decarboxylation of: 5-OH-Trp

A

5-OH-Trp → Serotonin

5-OH tryptophane decarboxylase

51
Q

Decarboxylation of Glutamate

A

Glutamate → Gamma-amino-butyrate (GABA)

Glutamate decarboxylase

52
Q

Decarboxylation of: Serine

A

Serine → Ethanolamine (Cholamine)

Serine decarboxylase

53
Q

Decarboxylation of: Cysteine

A

Cysteine → Cysteamine

Cys-decarboxylase

54
Q

Decarboxylation of: Cysteine → Taurine

A

Cysteine → cysteic acid → Taurine

55
Q

Decarboxylation of Aspartic acid

A

Aspartic acid → Beta-alanine

Asp-decarboxylase

56
Q

What is the role of taurine in bile salt synthesis?

A

Bile acids are conjugated with taurine to produce bile salts

57
Q

Decarboxylation of: Ornitine

A

Ornitine → Putrescine

Ornithine-decarboxylation

58
Q

Decarboxylation of: Lysine

A

Lysine → Cadaverine

Lysine-decarboxylase

59
Q

Cadaverine

A
  • Foul smelling
  • Produced by protein hydrolysis during putrefaction
60
Q

Location of carnosine

A

Muscle + Brain (Mammals)

61
Q

Location of Anserine

A

Muscle + brain (birds)

62
Q

The function of carnosine and anserine

A

Buffering lactic acid + RBCs

63
Q

Function of glutathione

A
  • Splits disulphide bonds of proteins (reduction)
  • Reduces thioredoxine
64
Q

Glutathione removes peroxides via which enzyme?

A

Glutathione peroxidase