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ZZZBiochemistry > Protein and Amino Acid Metabolism > Flashcards

Protein and Amino Acid Metabolism Flashcards

1
Q

What are the 3 components of the amino acid pool?

A

Body Protein
Dietary Protein
Synthesized Nonessential Amino Acids

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2
Q

What is defective in patients suffering from Hartnup Disease?

What does this lead to?

A

Defective transport of nonpolar or neutral amino acids like Tryptophan. Leads to an increased levels in the urine.

Leads to a failure to thrive in infants,

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3
Q

What is defective in patients suffering from Cystinuria? What does this lead to?

A

Defective transport of dimeric cystine and basic amino acids such as Arginine and Lysine

This leads to cystine crystals in the kidneys AKA kidney stones

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4
Q

What are the Essential Amino Acids?

A

PVT TIM HALL

Phenylalanine
Valine
Threonine

Tryptophan
Isoleucine
Methionine

Histidine
Arginine
Leucine
Lysine

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5
Q

What is the function of enteropeptidases/enterokinases?

A

To cleave trypsinogen into the active form of trypsin

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6
Q

Which 2 amino acids are ketogenic?

A

Leucine

Lysine

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7
Q

What are the 5 amino acids that are both glucogenic and ketogenic?

A 
Phenylalanine
Isoleucine
Tryptophan
Threonine
Tyrosine
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8
Q

What are the amino acids that are only glucogenic?

A

Find this out by process of elimination cause there are a lot of these.

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9
Q

What are transamination molecules? What are 2 examples used?

A

Molecules that transfer amino groups to an alpha-ketoacid

Aspartate + Alpha-ketoglutarate -> Glutamate + Oxaloacetate (This is encouraged by the enzyme Aspartate Aminotransferase (AST))

Alanine + Alpha-ketoglutarate -> Pyruvate + Glutamate (This is encouraged by the enzyme Alanine Aminotransferase (ALT))

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10
Q

What coenzyme do transaminases require? How does this affect AST and ALT?

A

Pyridoxyl 5’ Phosphate (PLP)

This increases ALT and AST after an MI

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11
Q

Which vitamin is Pyridoxyl 5’ Phosphate a derivative of??

A

Vitamin B6

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12
Q

During the metabolism of Methionine to Succinyl CoA, which is used in the TCA, what is the enzyme we need to know and what cofactor does it require?

A

Cystothionine B-Synthase

Requires Pyridoxal 5’ Phosphate (PLP)

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13
Q

What amino acid is used to form alpha-ketoglutarate in the TCA?

A

Glutamate, which can be formed from Glutamine

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14
Q

What disease occurs when there are branched chain amino acids and your urine smells sweet?

A

Maple Syrup Urine Disease

Acronym: I love vermont maple syrup

Isoleucine Leucine Valine Maple Syrup

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15
Q

What causes branched chain amino acids to be found in the urine? Essentially, what causes Maple Syrup Urine Disease?

What is the treatment?

A

When Branched chain alpha-keto acid dehydrogenase complex (BCKD) activity which results in branched chain ketoaciduria

Treatment is a synthetic diet that excludes branched chain amino acids like valine, leucine, and isoleucine

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16
Q

What causes Phenylketonuria (PKU)?

A

Caused by defects in the activity of phenylalanine hydroxylase (PAH), which causes phenylalanine to be converted into phenylpyruvate and phenyllactate, which causes a musty odor in the urine.

17
Q

What 2 molecules are Tryptophan used as derivatives for?

A

Serotonin -> Melatonin

Niacin -> NAD(P)+ *Note that this requires Vitamin B6

18
Q

What is Serine used as a derivative for?

A

Acetylcholine

19
Q

What 3 molecules are Tyrosine used as derivatives for?

A

Dopamine -> Norepinephrine -> Epinephrine
Thyroid Hormones (T3 and T4)
Melanin

20
Q

What is Glutamine used as a derivative for?

A

GABA

21
Q

What is Arginine used as a derivative for? What is the clinical relevance to this compound?

Note that this compound is also made up of two other amino acids, what are they?

A

Creatine Phosphate

Its isoform is Creatine Kinase (CK), which is diagnostic for myocardial infarctions

Made up of three amino acids:
Arginine
Glycine
Methionine

22
Q

What is the function of creatine phosphate?

A

energy storage in muscle, brain, and sperm

-quickly generates ATP and is used as our immediate energy source

23
Q

What causes Albinism?

A

This is due to a severe lack of melanin due to the blocking of the conversion of tyrosine to melanin due to defects in the enzyme tyrosinase

24
Q

How are patients with hyperthyroidism treated?

A

With agents that block iodination of thyroglobulin to decrease the production of T4 and T3

25
Q

How is ammonia removed in the brain verses other tissues?

A

In the brain: removed as glutamate and glutamine

In other tissues: removed as Glutamate and Alanine

26
Q

Describe the process of removing nitrogen from the brain.

A

In the brain, Alphaketoglutarate is converted to glutamate via glutamate dehydrogenase.

glutamate is converted to glutamine via glutamine synthase in the brain.

glutamine is able to leave the brain and move into the liver, where it is converted back into Glutamate via glutaminase. Nitrogen is removed from glutamine during this process and is converted into urea.

27
Q

Describe the process of removing excess ammonia from muscles.

A

Glutamate and pyruvate are used to form alanine in the muscle. Alanine then traverses to the liver and is broken down into glutamate and pyruvate by Alanine Aminotransferase (ALT). During this process it releases ammonia in the liver, which is then used to form urea.

28
Q

Describe the process of the urea cycle.

A

In the mitochondria, free ammonia combines with carbamoyl phosphate via the enzyme Carbamoyl Phosphate Synthetase I (rate limiting step). This compound combines with ornithine within the mitochondria to form Citrulline. Citrulline leaves the mitochondria and combines with Aspartate to form Arginine. Arginine is broken into Urea and Ornithine. Ornithine recycles back into the mitochondria.

Note that urea leaves cytoplasm and diffuses into the blood to be sent to the kidneys for excretion.

29
Q

Why is NH3 a toxic agent?

A

Due to its ability to permeate membranes

30
Q

What kinds of diets would increase or decrease ammonia output within the urine?

A

High protein diet would increase urea output

High carbohydrate diet would decrease urea output

ZZZBiochemistry (12 decks)

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