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Biochem > Amino Acids and Nitrogen > Flashcards

Amino Acids and Nitrogen Flashcards

1
Q

Essential AAs

A

PVT TIM HALL
Phenylalanine, Valine, Threonine
Tryptophan, Isoleucine, Methionine
Histidine, Leucine, Lysine

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2
Q

Acidic AAs

A

Aspartate and Glutamate

Negatively charged at body pH

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3
Q

Basic AAs

A

Arg, Lys, His

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4
Q

What is the most basic AA

A

Arg

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5
Q

What AAs are required in periods of growth

A

Arg and Histidine

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6
Q

What are arginine and lysine required for

A

Nuclear localization signals

High concentrations in histones

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7
Q

Why are lysine and arginine so basic

A

Extra ammonia group

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8
Q

What AA has no charge at body pH?

A

Histidine

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9
Q

What amino acid is important in catecholamine synthesis

A

Phenylalanine, Tyrosine

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10
Q

What happens if you iodinate tyrosine

A

Thyroxine

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11
Q

How is Dopa made

A

Converted from tyrosine with tyrosine hydroxylase + BH4

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12
Q

What makes melanin

A

Converted from Dopa

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13
Q

What makes dopamine

A

Dopa w/B6 and Dopa decarboxylase

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14
Q

What is dopamine converted to

A

NE, with vitamin C

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15
Q

What converts phenylalanine to tyrosine

A

Phenylalanine hydroxylase and BH4

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16
Q

What inhibits Dopa decarboxylase

A

Carbadopa

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17
Q

What stimulates conversion of NE to Epi?

A

Cortisol

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18
Q

What happens when break dopamine down?

A

Get HVA

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19
Q

What happens when NE broken down

A

VMA

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20
Q

What happens when Epi broken down

A

Metanephrine

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21
Q

What 3 things can you make from arginine?

A
  1. Creatine (can transfer phosphate to ATP)
  2. Urea
  3. NO (requires BH4)
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22
Q

What compounds is tryptophan converted to

A

Niacin and Serotonin

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23
Q

What is required to make niacin from tryptophan

A

B6

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24
Q

What is required to make serotonin from tryptophan

A

BH4 and B6

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25
What essential elements are made from niacin?
NAD+ and NADP+
26
What is the precursor to melatonin
Serotonin
27
What is histidine converted to and what is required
Histamine, requires B6
28
What AA is required to make porphyrin
Glycine, with B6
29
What AA is required to make GABA?
Glutamate, with B6
30
What amino acid derivatives require B6 as a cofactor?
``` Trp -> Niacin Trp -> Serotonin His -> Histamine Glycine -> Porphyrin Glutamate -> GABA ```
31
What are the derivatives of glutamate?
GABA (with B6) | Glutathione
32
Where does urea cycle take place
Liver
33
Rate limiting step in urea cycle
CPS-I
34
Where is CPS-I found
Mitochondria
35
What is CPS-II rate limiting enzyme of
Pyrimidine synthesis
36
What is ornithine transcarbamylase
An enzyme in urea cycle that uses ornithine and carbamoyl phosphate to make citruline
37
OTC deficiency
XR Can't undergo urea cycle -> Build up N and ammonia *Low BUN!
38
What is in excess in OTC deficiency
Carbamoyl phosphate
39
What is carbamoyl phosphate converted to in OTC?
Orotic acid
40
Symptoms in OTC deficiency
Hyperammonemia Can get this in liver disease too Slurring of speech, somnolence, vomiting, cerebral edema, blurry vision (=hepatoencephalopathy)
41
Most common urea cycle disorder
OTC deficiency
42
How to treat OTC deficiency
Decrease N load - eat low protein diet Phenylbutyrate - binds amino acids like glycine and glutamine and help excrete them Benzoate Biotin - can stimulate ornithine transcarbamylase if you have it
43
What amino acid is the precursor of porphyrin and heme
Glycine
44
What amino acid is the precursor of nitric oxide
Arginine
45
What amino acid is the precursor of GABA
Glutamate
46
What amino acid is the precursor of S-adenosyl-methionine
Methionine
47
What amino acid is the precursor of creatine?
Arginine
48
Compare CPS-1 to CPS-2
1: Urea cycle in Mt, N from ammonium 2: Pyrimidine synthesis in Cytosol, N from glutamine
49
What are the two ways to get PKU
1. Deficiency in Phe hydroxylase | 2. Deficiency on cofactor - BH4
50
What becomes an essential amino acid in PKU
Tyrosine
51
What happens to Phe in PKU
Becomes phenylketones
52
What causes neurotoxic effects in PKU
Excess Phe (not phenylketones)
53
Why do you have fair skin in PKU?
Can't go through pathway to make melanin
54
How is PKU treated
``` Avoid phenylalanine: high protein foods, aspartame Augment tyrosine (essential) +/- BH4 (tetrahydrobiopterin) ```
55
What happens to baby of pregnant mom who has PKU?
Microcephaly Intellectual disability Growth retardation Congenital heart defects
56
What is alkaptonuria
Ochronosis Congenital deficiency of "homogentisate oxidase" which is in the degradation of tyrosine to fumarate AR
57
What happens in alkaptonuria
Dark connective tissue, brown sclerae, urine turns black on prolonged exposure to air Arthralgias - b/c homogentisic acid gets deposited in CT and is toxic to cartilage
58
What causes albinism
Tyrosinase (can't make melanin) | Or, no melanocytes where they are supposed to be
59
What is homocystinuria
Excess homocystine by 3 different pathways
60
Clinical manifestations
``` Homocysteine in urine Mental retardation Osteoporosis, tall stature Kyphosis Atherosclerosis Lens subluxation (downward) ```
61
How to treat homocystinuria if it's a cystathionine synthase problem
Decrease dietary methionine Increase cysteine in diet (can't make it) Incr B12, Folate, B6
62
S-Adenosyl-methionine - why important
Transfers methyl units in body | Important for NE-> Epi and for synthesis of phosphocreatinine
63
How is SAM made
Methionine + ATP
64
What is needed to regenerate methionine
B12 and folate
65
Cystinuria
Defect of renal tubular AA for "COLA"
66
What does COLA stand for
Cysteine Ornithine Lysine Arginine
67
Sx of cystinuria
Cysteine kidney stones
68
How are cysteine kidney stones prevented
Acetazolamide - alkalinizes urine
69
MSUD
Branched chain a-ketoacid dehydrogenase complex deficiency --> build up of isoleucine, leucine, valine
70
Sx of MSUD
Intellectual deficiencies Severe CNS defects Death
71
Hartnup disease
AR defect of transportier in kidneys and intestines | Deficiency of neutral AAs, especially tryptophan
72
What is the pathophysiology of Hartnup disease
No tryptophan -> cant make niacin -> pellagra
73
A patient with PKU - what other dietary modifications besides restricting phenylalanine?
Incr tyrosine | Replace BH4

Biochem (10 decks)

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