Amino Acid metabolism Flashcards

(83 cards)

1
Q

Why would we break down amino acids

A

Protein turnover
Protein rich diet
Starvation/uncontrolled diabetes

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2
Q

Are amino acids stored in the body?

A

No

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3
Q

How to we get amino acids

A

Dietary
Synthesized
Protein degradation

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4
Q

What are the two steps in catabolizing excess amino acids

A

Step1: Removal of Nitrogen (amino group)
Step2: Carbon skeleton

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5
Q

Where are free amino acids found

A

Cells
Blood
Extracellular fluid

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6
Q

What happens to amino acids in a low energy situation

A

Amino Acids are oxidized to make ATP

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7
Q

What happens to amino acids in a low glucose state

A

AA sent to liver and turned into glucose

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8
Q

What happens to AA in high energy/lots of glucose

A

AA sent to liver and turned into fat

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9
Q

What can AA be made into

A
ATP
Glucose
Fat
Protein
Nitrogen compounds
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10
Q

How many AA can muscles oxidize?

A

6

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11
Q

How many AA can the liver oxidize

A

20

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12
Q

What is AA oxidation

A

Break down of AA into ATP

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13
Q

What is an AA first broken down to during catabolism

A
Amino Group
Carbon Skeleton (a-Keto acid)
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14
Q

What is the fate of the amino group of an AA

A

Urea and excreated

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15
Q

What is the fate of the carbon skeleton of an AA

A

ATP
Glucose
FA

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16
Q

What is the reaction that removes the Amino group of an AA? What enzyme is involved

A

Rxn: Transamination

Enzyme: Aminotransferases

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17
Q

What is the Amino group of an AA transfered to

A

A-ketogluterate

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18
Q

What are the reactants and products of Transaminoation

A

AA + a-ketogluterate
To
Keto acid + Glutamate

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19
Q

What is the importance of Glutamate in the body

A

It is used as a Amino Donor in bio-synthetic pathways

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20
Q

What determines the fate of a-keto acid

A
Energy charge
Hormones
Repiratory quotient
Glucose concentration
The tissue it is in
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21
Q

Where are most AA metabolized

A

The Liver

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22
Q

What transports AA to the liver

A

Glutamine

Alanine

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23
Q

What do you get when you combine Glutamate/Glutamine with a-ketoacid

A

a-ketogluterate (metabolite of krebs)

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24
Q

What do you get when you combine Alanine and a-ketoacid

A

Pyruvate (end metabolite of glycolosis)

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25
What do you get when you combine Aspartate and a-ketoacid
Oxaloacetate (Kreb cycle intermediate)
26
Where is Glutamate produced? Where is Glutamine produced
Glutamate: Liver (AA-->a-ketogluterate-->Glutamate) Glutamine: Extrahepatic tissues
27
What AA make up the highest concentration in the liver
Glutamine | Glutamate
28
Where is Glutamate in the liver transfered to in the liver
Cytosol to the mitochondria
29
What type of reaction removes the amino group off of Glutamate
Oxidative damination
30
What it produced from Oxidative deamination of Glutamate
NH4 (Ammonia) | a-Ketogluterate
31
What is the main transporter of Ammonia in the body
Glutamine Glutamate+NH3-->Glutamine
32
How does muscle act as a Nitrogen donor
Muscle uses AA for Nitrogen to make Glutamine for export
33
What are the nitrogen donors in skeletal muscle
``` Leucine Isoleucine Valine Glutamate Aspartate Asparagine ```
34
What enzyme turns glutamate into glutamine in muscles
Glutamine synthetase NH3+glutamate--->Glutamine
35
What enzyme hydrolyzes glutamine into glutamate
Glutaminase Glutamine-->glutamate+NH3
36
What are the two systems that need nitrogen from gluatamine?
Digestive system | Immune system
37
How to skeletal muscles produce alanine
Muscles give amino group from glutamate to pyruvate -->Alanine
38
What enzyme transferes the amio group from glutamate to pyruvate
Alanine aminotransferase
39
What does Alanine aminotransferase differ in liver and muscles
Muscles: lots of pyruvate --> pushes rxn to make alanine Liver: lots of alanine from muscles --> pushes rxn to make pyruvate
40
What is the steps in the muscles+liver of Glucose -alanine cycle
Muscles: Glucose --> Pyruvate --> Alanine --> Liver Liver: Alanine --> Pyruvate --> glucose --> Muscles
41
What cycle is used to turn alanine into glucose in the liver
Gluconeogenesis
42
what percentage of energy does alanine provide during exercise
5%
43
Where do the carbons in alanine come from?
Mucles glycogen
44
What enzyme transfers the amino group from glutamate to oxaloacetate. What is formed
Enz: Aspartate aminotransferase Prod: Aspartate
45
What is aspartate used for
Transporting Malate in and out of the mitochondria
46
What happens to excess nitrogen that is not used
liver converts it into urea and it is excreated
47
Why does nitrogen go to the liver
1) You have eaten too much protein | 2) you are in gluconeogeneis
48
What are the two enzymes in the liver that are entry points for aa to be converted into urea
Glutamate dehydrogenase Aspartate aminotransferase
49
What does the free NH3 in the liver need to be turned into in order to enter the urea cycle? What enzyme does it
Product: Carbamyol Phosphate Enz: Carbamoyl Phosphatase
50
What is the first step in the urea cycle
Carbamoyl phosphate + L-Ornithine --> L-citrulline
51
What enzyme is used in the first step of the urea cycle
Ornithine transcarbamoylase
52
What is the second step in the urea cycle
L-Citrulline --> Argininosuccinate
53
What enzyme is used in the second step of the urea cycle
Argininosuccinate
54
What AA provides a second nitrogen during the second step of the urea cycle
Aspartate
55
What is the third step in the urea cycle
Argininosuccinate --> L-arginine
56
What enzyme is used in the third step of the urea cycle
Arginiosuccinate lyase
57
What is a by-product of the third step of the urea cycle
Fumarate
58
What is the 4th step of the urea cycle
L-Arginine --> L-ornithine
59
What step of the urea cycle produces urea
step 4 L-arginine --> L-Ornithine
60
What enzyme is used to turn L-arginine into --> L-Ornithine
Arginase
61
Where does some of the urea produced by the urea cycle diffuse into
GI tract and excreted in feces
62
How many nitrogens are on urea
2 One from aspartate one from free NH3
63
What happens to the concentration of Glutamate and alanine in blood plasma during exercise
Glutamate = Decrease Alanine = Increase
64
How much can ATP turn over increase during exercise. What does this mean for the cell?
100 fold Kreb cycle intermediates need to increase 4-10 fold
65
What are the Branched Chain Amino Acids (BCAA's)
Leucine Isoleucine Valine
66
What AA constitute 90% of muscles AA uptake after a meal
Leucine, Isoleucine, Valine
67
How much does glutamine release increase after a meal
It doubles
68
What amino acids are released in an amounts less than what is taken in
BCAA's Glutamate Aspartate Asparagine
69
What amino acids are released in an amount more than what is taken in
Alanine | Glutamine
70
What step of the urea cycle produces urea
step 4 L-arginine --> L-Ornithine
71
What enzyme is used to turn L-arginine into --> L-Ornithine
Arginase
72
Where does some of the urea produced by the urea cycle diffuse into
GI tract and excreted in feces
73
How many nitrogens are on urea
2 One from aspartate one from free NH3
74
What happens to the concentration of Glutamate and alanine in blood plasma during exercise
Glutamate = Decrease Alanine = Increase
75
How much can ATP turn over increase during exercise. What does this mean for the cell?
100 fold Kreb cycle intermediates need to increase 4-10 fold
76
What are the Branched Chain Amino Acids (BCAA's)
Leucine Isoleucine Valine
77
What AA constitute 90% of muscles AA uptake after a meal
Leucine, Isoleucine, Valine
78
How much does glutamine release increase after a meal
It doubles
79
What amino acids are released in amounts less than what is taken in
BCAA's Glutamate Aspartate Asparagine
80
What amino acids are released in amount more than what is taken in
Alanine | Glutamine
81
When are amino acids turned into glucose
Starvation Low carb intake Exercise
82
What two amino acids can not be turned into glucose
Leucine | Lysine
83
How are amino acids turned into fat
AA --> a-ketogluterate --> acetyl CoA