protein structure and function Flashcards
1
Q
what determines the properties of proteins?
A
side chains
2
Q
which type of amino acids are proteins composed of?
A
L
3
Q
What are the nonpolar amino acids?
A
glycine
alanine
valine
leucine
isoleucine
phenylalanine
tryptophan
methionine
proline
4
Q
what are the uncharged polar amino acids?
A
serine
threonine
tyrosine
asparagine
glutamine
cysteine
5
Q
what are the acidic amino acids?
A
aspartate
glutamate
6
Q
what are the basic amino acids?
A
histidine
lysine
arginine
7
Q
Asp, D
A
aspartate
8
Q
Glu, E
A
glutamate
9
Q
His, H
A
histidine
10
Q
Lys, K
A
Lysine
11
Q
Arg, R
A
arginine
12
Q
Ser, S
A
serine
13
Q
Thr, T
A
threonine
14
Q
Tyr, Y
A
Tyrosine
15
Q
Asn, N
A
Asparagine
16
Q
Gln, Q
A
Glutamine
17
Q
Cys, C
A
Cysteine
18
Q
Gly, G
A
Glycine
19
Q
Ala, A
A
Alanine
20
Q
Val, V
A
Valine
21
Q
Leu, L
A
leucine
22
Q
Ile, I
A
Isoleucine
23
Q
Phe, F
A
Phenylalanine
24
Q
Trp, W
A
Tryptophan
25
Met, M
methionine
26
Pro, P
Proline
27
which amino acids play an important role in buffering changes in physiological pH?
Histidine and Cysteine
28
where are nonpolar amino acids found in a protein?
interior, membrane proteins
29
where are polar amino acids found in a protein?
the surface of soluble proteins
30
primary structure
the order of amino acids in the protein
31
what type of bonds form peptide bonds?
covalent
32
why is rotation around the alpha carbon limited?
steric hindrance (except for gly)
33
what amino acid forms disulfide bonds due to their thiol groups?
cysteine
34
secondary structure
local structures formed by interactions of amino acid chains
35
alpha helix
stabilized by hydrogen bonds involving peptide backbone CO and NH
-sidechains project outward
-3.4 amino acids per turn
36
which amino acids are not found in an alpha helix?
-proline breaks the helix by introducing a bend
-glycine is too floppy
37
beta sheet
-peptide chains form bonds with neighbors
-stabilized by hydrogen bonds involving peptide backbone CO and NH
-side chains outward
-chains can run parallel or antiparallel
38
unstructured polypeptide is referred to as ________________
random coil
39
motifs/supersecondary structures
-formed by aggregation of alpha helices, beta sheets
-beta barrels and sandwiches are common structural motifs
40
tertiary structure
-overall structure of a protein or subunit
-motifs condense to form domains and entire protein subunits-protein folding
41
when do polypeptides begin to fold into secondary structure?
as soon as they are translated
42
where does protein folding occur?
cytoplasm and ER
-often assisted by chaperones/heat shock proteins
43
what stabilizes higher order structures?
interactions involving side chains
44
delta G/free energy
must be negative for reaction to be spontaneous
deltaG=deltaH - TdeltaS
45
delta H/enthalpy
energy consumed/released as heat but forming/breaking bonds
-charge charge interactions are highly favorable
-energy is released when salt bridges form
-delta H is negative
46
delta S/entropy
-disorder in system
-everything tends toward chaos
47
what drives protein folding in aqueous solutions?
positive entropy due to freeing water/hydrophobic effect
48
what can denature protein structure?
-chemical agents
-heat
-cold
-(disrupts the hydrophobic effect maintaining the folded state)
49
quaternary structure
-interactions of individual proteins or subunits within a functional complex
-can be composed of multiple subunits
-ex. hemoglobin or actin
50
which amino acids can be phosphorylated?
serine, threonine, tyrosine
51
