amino acids
R
I o
H 0
H R,
10
H
i
O H R,
%R2 O
In co i i
11 X
-
c -
-
-
+
- -
-
x condensation
->
-
-
b -
c -
N -
x
-
c H20
+
'ohi it oH
peptide
it
/
H ↓
H
/
'oh ⑫drolusis H ↓ bond ↓
&
proteases ↑
H
amine group carboxyl group dipeptide
This reaction takes place in ribosomes to conthesise proteins.
proteins
primary structure:the specific order ofamino acids in
a polypeptide,determines its a conformation
↳ determined by the DNA sequence of the gene which encodes thatpolypeptide.
secondary structure:the curling or folding ofthe primary structure into a-helixand p-pleated sheets due to hydrogen bonding.
-- f
f
-
-
o R
p
R R
↑
b
1
- -
i -
-
-
c -
c -
-
c
-
c
-
↓i ii vi ↓
68 +
+
f+
&
ribonds form along the peptide chain due to polarity
tertiary structure:the overalled shape a
of
polypeptide chain
esubunits
quaternary structure:comprised ofatleasttwo polypeptide chains.
L
may contain prosthetic groups non-protein molecules which form partofthe structures to help the protein carry outi ts function conjugated proteins.
↳ eg:harm in haemoglobin binds to oxygen
Type of bonding in the 3 and 40 structure depend on the R groups oft he amino acids. Types ofbonding include:
hydrogen bonding
↳ weak;
easily broken by high temperature or pHchanges
hydrophobic interactions
a
↳
non-polar amino acids (having uncharged R groups) tend to cluster together, excluding water molecules 7
hydrophobic
ni
found in the centre ofproteins.
3 interactions
hydrophilic interactions
↳ found on the surface proteins,
of where they can interactw ith water molecules
-
polypeptide
↑
ionic bonds
↳
R groups are oppositely charged and so are each other
attracted to
↳ broken by changes in pH
disulfide bridges
5
↳
relatively strong; notbroken by high temperatures or pHchanges
Tertiary ifthese bonds are formed on the same polypeptide chain.
↓
Quaternary itformed between differentsubunits. ionic bond
Globular proteins:often have metabolic roles.
Have an approximately spherical shape
soluble in water;have hydrophilic amino acids on their surface.
↳
hydrophobic amino acids found in the centre ofthe protein.
eg:haemoglobin Two subunits two B subunits
Quaternary structure with four polypeptide subunits
-
Reversibly binds to oxygen in the lungs, and releases iti n the body tissues
-
-
conjugated protein;each subunitcontains the prosthetic group harm which has an F
ion where the O2 binds to -402 bind to 1b
-
can
R
I o
H 0
H R,
10
H
i
O H R,
%R2 O
In co i i
11 X
-
c -
-
-
+
- -
-
x condensation
->
-
-
b -
c -
N -
x
-
c H20
+
'ohi it oH
peptide
it
/
H ↓
H
/
'oh ⑫drolusis H ↓ bond ↓
&
proteases ↑
H
amine group carboxyl group dipeptide
This reaction takes place in ribosomes to conthesise proteins.
proteins
primary structure:the specific order ofamino acids in
a polypeptide,determines its a conformation
↳ determined by the DNA sequence of the gene which encodes thatpolypeptide.
secondary structure:the curling or folding ofthe primary structure into a-helixand p-pleated sheets due to hydrogen bonding.
-- f
f
-
-
o R
p
R R
↑
b
1
- -
i -
-
-
c -
c -
-
c
-
c
-
↓i ii vi ↓
68 +
+
f+
&
ribonds form along the peptide chain due to polarity
tertiary structure:the overalled shape a
of
polypeptide chain
esubunits
quaternary structure:comprised ofatleasttwo polypeptide chains.
L
may contain prosthetic groups non-protein molecules which form partofthe structures to help the protein carry outi ts function conjugated proteins.
↳ eg:harm in haemoglobin binds to oxygen
Type of bonding in the 3 and 40 structure depend on the R groups oft he amino acids. Types ofbonding include:
hydrogen bonding
↳ weak;
easily broken by high temperature or pHchanges
hydrophobic interactions
a
↳
non-polar amino acids (having uncharged R groups) tend to cluster together, excluding water molecules 7
hydrophobic
ni
found in the centre ofproteins.
3 interactions
hydrophilic interactions
↳ found on the surface proteins,
of where they can interactw ith water molecules
-
polypeptide
↑
ionic bonds
↳
R groups are oppositely charged and so are each other
attracted to
↳ broken by changes in pH
disulfide bridges
5
↳
relatively strong; notbroken by high temperatures or pHchanges
Tertiary ifthese bonds are formed on the same polypeptide chain.
↓
Quaternary itformed between differentsubunits. ionic bond
Globular proteins:often have metabolic roles.
Have an approximately spherical shape
soluble in water;have hydrophilic amino acids on their surface.
↳
hydrophobic amino acids found in the centre ofthe protein.
eg:haemoglobin Two subunits two B subunits
Quaternary structure with four polypeptide subunits
-
Reversibly binds to oxygen in the lungs, and releases iti n the body tissues
-
-
conjugated protein;each subunitcontains the prosthetic group harm which has an F
ion where the O2 binds to -402 bind to 1b
-
can
