Flashcards in BIOCHEM 4 - AMINO ACIDS Deck (70):
1
Essential Amino acids
L, I, V, H, K, M, F, T, W
2
Non-essential amino acids
A, R, N, D, C, E, Q, G, P, S, Y
3
aa (obtained from nutrition)
Essential Amino acids
4
aa (synthesized by the body)
Non-essential amino acids
5
properties of AA (4)
Amphoteric
dipolar
optically active
tetrahedral structure
6
– reference to determine if the
amino acid has L- or D-configuration
α-amino group
7
All amino acids in naturally occurring proteins are
L-isomers
8
◦ derived from glutamate; neurotransmitters (has something to do with the brain)
GABA
9
GABA is derived from
glutamate
10
◦ derived from tryptophan; important in sleep
Serotonine
11
serotonine derived from
derived from tryptophan
12
3. Thyroxine
derived from tyrosine
13
indole acetic acid
4. Dopamine –
14
– side chain is a primary alcohol; looks like Ala with -OH
Serine
15
side chain is a secondary alcohol;
◦ Threonine
16
has two chirality centers
threonine and isoleucine
17
contains a thiol group; important in disulfide linkages; weak acid; can form H-bonds
◦ Cysteine
18
- ionized cysteine is -----, while the protonated form is much --------than serine.
polar
less polar
19
also has the ability to form covalent bonds called disulfide bonds between cysteine side chains.
Cysteine
20
– side chain is phenolic –OH; borderline case
Tyrosine
21
not very soluble in water, but contains a polar hydroxyl group in the para position of the phenyl ring
Tyrosine
22
amide groups do not become charged at biologically relevant pH values (i.e. pH 2-12), true or false
TRUE
23
simplest amino acid
GLYCINE
24
does not really have a polar or non-polar character
GLYCINE
25
- has much less steric hindrance than the other AAs;
GLYCINE
26
No chiral center/achiral
GLYCINE
27
no asymmetric carbon
GLYCINE
28
– side chain is isopropyl
Valine
29
side chain is isobutyl
Leucine
30
side chain is sec-butyl; has 2 chiral carbons
Isoleucine –
31
more hydrophobic than cysteine (S-containing amino acids)
Methionine
32
start amino acid
Methionine
33
having thioether
Methionine
34
– cyclic but not aromatic; 2ndary α-amino group or α-imino acid
- has a conformationally restricted structure
Proline
35
behaves more like a polar amino acid since ----- has a fairly high tendency to appear on the solvent-exposed surface of proteins
proline
36
– has an indole ring; borderline hydrophobic/polar
Tryptophan
37
what AA has the proton attached to the indole nitrogen can act as a hydrogen bond donor to water or other hydrogen bond acceptors
Tryptophan
38
majority of the large tryptophan side-chain is polar or not?.
non-polar
39
acidic form of asparagines; β-carboxyl group
Aspartate-
40
acidic form of glutamine; γ-carboxyl group
Glutamate–
41
– has a primary amino group
protonated at pH 7.0
◦ Lysine
42
contains ε-amino group
◦ Lysine
43
diamino acid
◦ Lysine
44
– most basic amino acid
Arginine
45
contains guanido group
Arginine
46
guanidinium ion always protonated
Arginine
47
heterocyclic ring side chain; not aromatic
Histidine
48
contains imidazole
Histidine
49
only amino acid that functions as buffer in physiological range
Histidine
50
all are very hydrophobic
absorbs UV at 280 nm
aromatic amino acids
Tyrosine, Tyr (Y)
Tryptophan, Trp (W)
Phenylalanine, Phe (F)
51
contain carboxyl groups (weaker than α-carboxyl group)
negatively charged at physiological pH;
Aspartate, Asp (D)
Glutamate, Glu (E)
52
present as conjugate bases
carboxyl groups function as nucleophiles in some enzymatic reactions
Aspartate, Asp (D)
Glutamate, Glu (E)
53
classified as β-branched
have greater steric hindrance
exhibit more restricted conformational flexibility
Valine, Val (V)
Isoleucine, Ile (I)
Threonine, Thr (T)
54
18 of the 19 L-amino acids have --- configuration
S
55
cysteine has -- configuration
R
56
is neither very
hydrophobic nor very hydrophilic.
Proline
57
As the pH increases, the charge on the molecule becomes
more negative,
58
as the pH decreases,
the charge on the molecule becomes
more positive.
59
zero net charge state is known as the
zwitterionic state
60
is capable of both accepting
and donating protons
zwitterion
61
characteristic of free amino acids with non-ionizable side chains near pH
7.0
zwitterion
62
At pH >> pKa, the ionizable group will be .
-
deprotonated
63
At pH >> pKa, For carboxylic acids, the group will be ____ charged;
negatively
64
At pH >> pKa, amines will be ____
neutral
65
At pH << pKa, the ionizable group will be _______
protonated.
66
At pH << pKa, For carboxylic acids, the group will be __
neutral
67
At pH << pKa, amines will be _____
positively charged
68
has a chemically basic side chain but acidic pKa
histidine
69
pKa values of amino groups of common AA
occur in a range from pH 9 to pH 11
70