Ch. 3: Amino Acids Flashcards

1
Q

What are the nonpolar hydrophobic amino acids?

A

valine, alanine, glycine, leucine, isoleucine, proline, methionine, phenylalanine, tryptophan

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2
Q

What are the polar, positively charged, basic amino acids?

A

histidine, lysine, arginine

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3
Q

What are the polar, negatively charged, acidic amino acids?

A

aspartate, glutamate

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4
Q

What are the polar, neutral amino acids?

A

cysteine, asparagine, glutamine, serine, threonine, tyrosine

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5
Q

What are the essential amino acids?

A

methionine, isoleucine, leucine, lysine, valine, phenylalanine, threonine, tryptophan

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6
Q

What are the conditionally essential amino acids?

A

glutamine, histidine, arginine

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7
Q

What are the non-essential amino acids?

A

glycine, proline, serine, tyrosine, aspartate, alanine, asparagine, cysteine, glutamate

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8
Q

Glycine: 4 important functions?

A

1) collagen: every third position a.a.
2) biosynthesis: porphryns & purines
3) bile acids conjugation
4) neurotransmitter: + or -

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9
Q

Disease associated with glycine?

A

non-ketotic hyperglycinemia (NKH): Inborn error of glycine degradation, effects CNS ➡️ death

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10
Q

Alanine: important function?

A

Link between a.a. & CHO metabolism

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11
Q

Valine, leucine, isoleucine: important function?

A

Stabilize 3D structure (hydrophobic) of polymer

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12
Q

Disease associated with valine, leucine, & isoleucine?

A

Maple syrup urine disease

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13
Q

Disease associated with phenylalanine?

A

Phenylketonuria: low levels of phenylalanine hydroxylase ➡️ build up of Phe

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14
Q

What are the 4 hydroxylation reactions that need BH4 as cofactor?

A

1) Phe ➡️ Tyr
2) Tyr ➡️ L-dopa
3) Trp ➡️ S-hydroxytrp
4) Arg ➡️ NO + citrulline

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15
Q

Tryptophan: important function?

A

Precursor for serotonin, melatonin, nicotinamide

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16
Q

Methionine: important function?

A

Methyl group donor (SAM)

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17
Q

Proline: 2 important functions?

A

1) intro restrictions on folding of polypeptide chain

2) collagen synthesis

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18
Q

What are the 2 important hydroxylases for collagen synthesis? What vitamin is needed for hydroxylase rxn?

A

Proline & lysine hydroxylase

Vitamin C

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19
Q

Aspartate: important function?

A

On surface of water-soluble proteins

20
Q

Glutamate: important function?

A

+ neurotransmitter in brain

21
Q

Disease associated with glutamate? Drugs that help treat?

A

Amyotrophic lateral sclerosis (ALS): glu excitotoxicity

Riluzole & gabapentin (GABA analog)

22
Q

Gamma-carboxyglutamate: important function? What vitamin is needed for formation?

A

Blood coagulation & anti-coagulation proteins

Vitamin K

23
Q

Lysine: 4 important functions?

A

1) linked to biotin, lipoic acid, retinal
2) collagen synthesis
3) cross links for tensile strength & insolubility in elastin & collagen
4) blood clotting: cross-linking in fibrin

24
Q

Histidine: 2 important functions?

A

1) essential for infants & uremia pts

2) precursor for histamine (His - carboxyl group)

25
What are the 2 histamine receptors? Where are they found? Antagonizing of these receptors treats what diseases?
H1: smooth muscle contraction; Tx allergic disorders H2: secrete HCl in stomach, ⬆️ ❤️ rate; Tx gastric ulcers
26
What toxins bind to dipthamide (inhibits translation)?
1) Diphtheria 2) Cholera 3) Pertussis
27
Arginine: 2 important functions?
1) creatine synthesis, urea cycle | 2) NO synthesis
28
Serine & threonine: 2 important functions?
1) form esters with phosphoric acid 2) form glycosides with sugars (O-linked) Used in regulatory reactions for proteins
29
Cysteine: important function?
Forms disulfide bridges (SS bonds) ➡️ cystine Used in protein folding
30
Selenocysteine: important function?
In active sites of redox reaction enzymes
31
Disease associated with selenocysteine?
Keshan disease (essential trace element)
32
Tyrosine: 3 important functions?
1) sulfated in gastrin & CCK 2) phosphorylated in insulin, EGF, PDGF, ILG 3) Precursor for thyroxine, catecholamines, melanin, Phe
33
Disease associated with tyrosine?
Tyrosinemia (tyrosinosis): can't break down tyrosine
34
Glutamine: 3 important functions?
1) synthesis of purines & pyrimidines 2) acid/base regulation (urea ➡️ NH3 ➡️ NH4+ + H+) 3) boosts immunity of surgical pts
35
Beta-alanine: function?
Part of pantothenic acid (vit B5)
36
Taurine: 2 functions?
1) present in CNS | 2) conjugate bile acids
37
GABA (gamma-aminobutyric acid): function?
- neurotransmitter, important in ALS
38
Hypoglycin A: importance?
Causes severe hypoglycemia when ingested
39
What is D-penicillamine used to treat?
Chelates metals; Tx Wilson's disease (copper accumulation in pupils)
40
What diseases is N-acetylcysteine used to treat?
1) Acetaminophen toxicity 2) replenish glutathione stores in liver 3) Cystic fibrosis 4) prevents further renal impairment
41
What disease is gabapentin used to treat?
ALS; anticonvulsant
42
What is pI (isoelectric point)? Equation?
pH at which molecule has 0 net charge pI = (pK1 + pK2 / 2)
43
What amino acids have buffering capacity in physiological pH?
Cysteine & histidine
44
What amino acids does trypsin cleave at?
Lys & Arg at carboxy end
45
What amino acids does chymotrypsin cleave at?
Phe, Trp, & Tyr at carboxy end
46
What amino acids does cyanogen bromide cleave at?
Met at carboxy end