Amino Acids Flashcards
1
Q
Alanine
A
Ala - A
- location: various locations
- hydrophobic
- aliphatic
- only a methyl group
- quite frequent (7.7%)
2
Q
Arginine
A
Arg - R
- location: on the surface of proteins
- hydrophilic
- basic (pKa 12.5)
- aliphatic
- planar guanidium group
- long, flexible amino acid
3
Q
Asparagine
A
Asn - N
- location: surface
- hydrophilic
- neutral, polar - carboxamide group
- aliphatic
- sometimes glycosylated
4
Q
Aspartate
A
Asp - D
- location: surface
- hydrophilic
- acidic (pKa 3.5) - carboxylate group
- aliphatic
5
Q
Cysteine
A
Cys - C
- location: disulphides
- ionizable (pKa 8.5)
- aliphatic
- thiol group (SH)
- oxidation ⇒ cystine (joint cysteines)
- reduction ⇒ 2 cysteines
- rare (2.0%)
6
Q
Glutamate
A
Glu - E
- location: surface
- hydrophilic
- acidic (pKa 4.5) - carboxylate group
- aliphatic
7
Q
Glutamine
A
Gln - Q
- location: surface
- hydrophilic
- neutral, polar - carboxamide group
- aliphatic
8
Q
Glycine
A
Gly - G
- location: in various locations and in loops
- hydrophobic
- aliphatic
- no R-group (not CHIRAL)
- quite common (7.4%)
9
Q
Histidine
A
His - H
- location: active sites
- hydrophilic
- basic (pKa 6.5) - imidazole group
- aromatic
- good for enzymatic activity (pKa close to 7)
- rare (2.3%)
10
Q
Isoleucine
A
Ile - I
- location: in the interiors
- hydrophobic
- aliphatic
- same mass as leucine
11
Q
Leucine
A
Leu - L
- location: in the interiors
- hydrophobic
- aliphatic
- most common amino acid (8.5%)
12
Q
Lysine
A
Lys - K
- location: surface
- hydrophilic
- basic (pKa 10.5)
- aliphatic
- can undergo acetylation
13
Q
Methionine
A
Met - M
- location: interior
- hydrophobic
- aliphatic
- contains sulphur (thioether)
- rare (2.4%)
14
Q
Phenylalanine
A
Phe - F
- location: interiors
- hydrophobic
- aromatic - phenyl group
- can rotate around its methyl group
15
Q
Proline
A
Pro - P
- location: surfaces and loops
- not aromatic (ring can pucker)
- pyrrolidine that circles back onto the peptide nitrogen (cyclic)
16
Q
Serine
A
Ser - S
- location: surface
- neutral, polar - hydroxyl group
- aliphatic
- sometimes phosphorylated/glycosylated
17
Q
Threonine
A
Thr - T
- location: surface
- hydrophilic
- polar, neutral - hydroxyl group
- sometimes glycosylated/phosphorylated
- has 2 chiral centres
18
Q
Tyrosine
A
Tyr - Y
- location: interior
- hydrophobic
- ionizable (pKa 10) - phenol group
- aromatic
- absorbs UV (280nm)
19
Q
Tryptophan
A
Trp - W
- location: interior
- mostly hydrophobic, but NH group has some hydrophilic property
- aromatic - indole group
- absorbs UV (280nm)
- fluoresces at different wavelengths
- most uncommon amino acid (1.4%)
20
Q
Valine
A
Val - V
- location: interior
- hydrophobic
- aliphatic
21
Q
What are the hydrophilic acidic amino acids?
They have carboxylate groups
A
- Asp (D)
- Glu (E)
22
Q
What are the hydrophilic basic amino acids?
A
- Lys (K)
- Arg (R)
- His (H)
23
Q
What are the hydrophilic, neutral, polar amino acids?
A
- Asn (N)
- Gln (Q)
- Ser (S)
- Thr (T)
24
Q
What are the hydrophobic aliphatic amino acids?
they have methyl groups
A
- Ala (A)
- Val (V)
- Leu (L)
- Ile (I)
- Met (M)
25
Q
What are the hydrophobic, aromatic amino acids?
A
- Phe (F)
- Tyr (Y)
- Trp (W)
