PROTEINS

• Natural polymers• C,H,O,N,(S)• Monomer is Amino Acids• Growth• Repair• Hormones• Enzymes• Antibodies• Energy Source

PROTEINS

• 15% of our bodies• Composed of 20 amino

acids• 10 we cannot synthesise

and store (essential amino acids)

• We get them from food• A Complete Protein

contains all 10 (eg Casein)

2-amino acids

• Contain carboxyl group and amine (amino) group

• Colourless• Crystalline solids• Exist as Zwitterions• Therfore high m.p.• Soluble in water• Amphoteric

Zwitterions

Lysine

• Basic amino acid

Aspartic Acid

• Acidic amino acid

Amino Acids

• Amphoteric nature makes it possible to act as buffers

Condensation Reaction

PRIMARY STRUCTURE

• The sequence of amino acids

• 3 letter codes used• A tripeptide would have

3 amino acids in sequence

Secondary Structure

• Manner in which protein folds

• Intramoleculer hydrogen bonding important

• Between O on carbonyl group and H on amine

• Alpha-helix• Beta-pleated sheets

Tertiary Structure

• Overall 3D shape• Covalent bonding (eg

disulphide bridges)• H-bonding• Salt bridges

(electrostatic attraction)• Affect of R group (eg

polarity, hydrophobic interactions)

Quarternary Structure

• How subunits join together

• Haemoglobin

Denaturing

• Heat• Ionising radiation• Strong acids, bases• Concentrated salt

solutions• Organic solvents• Detergents