Amino Acids Flashcards
1
Q
A / Ala
A
Hydrophobic
2
Q
Arg / R
A
Positively Charged
3
Q
Asn / N
A
Polar Uncharged
4
Q
Asp / D
A
Negatively Charged
5
Q
Cys / C
A
- Thiol group (-SH) forms a disulfide bridge
- In a reducing environment (intracellular space containing antioxidants), cysteines are separated (protonated thiols)
- In an oxidizing environment (extracellular space), cystines form disulfide bridges (deprotonated thiols)
6
Q
Glu / E
A
Negatively Charged
7
Q
Gln / Q
A
Polar Uncharged
8
Q
Gly / G
A
- simplest of all amino acids
- The alpha carbon is not chiral because the side chain is H
- very flexible / allows for free rotation
- alpha helix breaker- disrupts alpha helices by introducing kinks
9
Q
His / H
A
- Positively Charged
- pKa close to physiological pH - exists in both protonated and deprotonated forms
- useful at active site of protein where it can stabilize and destabilize a substrate
10
Q
Ile / I
A
Hydrophobic
11
Q
Leu / L
A
Hydrophobic
12
Q
Lys / K
A
Positively Charged
13
Q
Met / M
A
Hydrophobic
14
Q
Phe / F
A
Hydrophobic
15
Q
Pro / P
A
- Side chain wraps around and forms second covalent bond with amino nitrogen forming a secondary alpha amino group
- alpha helix breaker - disrupts alpha helices by introducing kinks
16
Q
Ser / S
A
Polar Uncharged
17
Q
Sec / U
A
- Selenol group - deprotonoated at physiological pH, used to influence nucleophilicity of the active site
18
Q
Thr / T
A
Polar Uncharged
19
Q
Trp / W
A
Hydrophobic
20
Q
Tyr / Y
A
Hydrophobic
21
Q
Val / V
A
Hydrophobic
