The Structure of Proteins. Functions of Proteins Fibrous proteins – structural, e.g. collagen....
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Transcript of The Structure of Proteins. Functions of Proteins Fibrous proteins – structural, e.g. collagen....
The Structure of Proteins
Functions of Proteins
• Fibrous proteins – structural, e.g. collagen. • Globular proteins – metabolic functions, e.g.
haemoglobin. • It is their structure that allows them to carry
out their functions.
Structure of Proteins
• Monomer units of proteins are called amino acids.
Structure of ProteinsAmino Acids
C
Structure of ProteinsAmino Acids
C
Structure of ProteinsAmino Acids
CNH
H
AMINO GROUP
C
Structure of ProteinsAmino Acids
CNH
H
AMINO GROUP
C
Structure of ProteinsAmino Acids
CNH
H
AMINO GROUP
O
OC
H
CARBOXYL GROUP
H
Structure of ProteinsAmino Acids
CNH
H
AMINO GROUP
O
OC
H
CARBOXYL GROUP
H
Structure of ProteinsAmino Acids
CNH
H
AMINO GROUP
O
OC
H
CARBOXYL GROUP
H
R-GROUP (Variant)
Structure of ProteinsAmino Acids
CNH
H
AMINO GROUP
O
OC
H
CARBOXYL GROUP
H
R-GROUP (Variant)
Structure of Proteins
PRIMARY STRCUTURE – Polypeptides• Polypeptides are composed of amino acids
bonded to each other, like beads on a string• The bond that holds them together is called a
peptide bond• They are formed by loss of water so is called a
condensation reaction.
Structure of Proteins
PRIMARY STRCUTURE – Polypeptides
Structure of Proteins
PRIMARY STRCUTURE – Polypeptides• -OH from carboxyl group• -H from amino group• Forms peptide bond
Structure of Proteins
Secondary Structure – α helix
+ve
-ve
Structure of Proteins
Tertiary Structure – α helix• 3D structure is formed by further bonds,
depending on the function• Disulphide bonds – strong and not easily broken
down• Ionic bonds – easily broken down by changes in
pH (carobxy/amino groups)• Hydrogen bonds – numerous be very easily
broken down
Functions of Proteins
• Fibrous proteins – structural, e.g. collagen. • Globular proteins – metabolic functions, e.g.
haemoglobin. • It is their structure that allows them to carry
out their functions. • i.e. the 3D structure is v.v.v important in
carrying out it’s function• Makes proteins distinctive – interacting with
other molecules
Structure of Proteins
Quaternary Structure • Complex molecules containing many
polypeptide chains
Structure of ProteinsExample – haemoglobin:
Test for proteins