Ch. 3: Amino Acids Flashcards Preview

Medical Biochemistry > Ch. 3: Amino Acids > Flashcards

Flashcards in Ch. 3: Amino Acids Deck (46):
1

What are the nonpolar hydrophobic amino acids?

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

2

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

histidine, lysine, arginine

3

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

aspartate, glutamate

4

What are the polar, neutral amino acids?

cysteine, asparagine, glutamine, serine, threonine, tyrosine

5

What are the essential amino acids?

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

6

What are the conditionally essential amino acids?

glutamine, histidine, arginine

7

What are the non-essential amino acids?

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

8

Glycine: 4 important functions?

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

9

Disease associated with glycine?

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

10

Alanine: important function?

Link between a.a. & CHO metabolism

11

Valine, leucine, isoleucine: important function?

Stabilize 3D structure (hydrophobic) of polymer

12

Disease associated with valine, leucine, & isoleucine?

Maple syrup urine disease

13

Disease associated with phenylalanine?

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

14

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

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

15

Tryptophan: important function?

Precursor for serotonin, melatonin, nicotinamide

16

Methionine: important function?

Methyl group donor (SAM)

17

Proline: 2 important functions?

1) intro restrictions on folding of polypeptide chain
2) collagen synthesis

18

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

Proline & lysine hydroxylase

Vitamin C

19

Aspartate: important function?

On surface of water-soluble proteins

20

Glutamate: important function?

+ neurotransmitter in brain

21

Disease associated with glutamate? Drugs that help treat?

Amyotrophic lateral sclerosis (ALS): glu excitotoxicity

Riluzole & gabapentin (GABA analog)

22

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

Blood coagulation & anti-coagulation proteins

Vitamin K

23

Lysine: 4 important functions?

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

Histidine: 2 important functions?

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