Enzymes Make sure you revise: What Enzymes are Enzymes structure Factors affecting enzyme action Enzymes in digestion Making use of enzymes Enzymes in industry

Enzymes and their structure + + ↔ ↔ enzyme reactant + enzyme-reactant complex ↔ products Enzymes are biological catalysts – they speed up reactions in living things. Enzymes are protein molecules made up of long chains of amino acids. These long chains are folded to produce a special shape enabling other molecules (substrate) to fit into the enzyme (active site).

Factors affecting enzyme action denatured normal heat pH The shape of the enzyme is vital to its function. The main factors affecting enzyme action are 1.) temperature and 2.) pH 1.) High temperatures can destroy the enzymes ‘special shape’ so it becomes denatured. 2.) Different enzymes work best at different pH values.

Enzymes in digestion Enzyme: Amylase Protease Lipase Produced in: - Salivary glands - Pancreas - Small intestine Stomach Pancreas Small intestine Job: Catalyses the breakdown of starch into sugars Catalyses the breakdown of proteins into amino acids Catalyses the breakdown of lipids (fats and oils) into fatty acids and glycerol Where: - Mouth Also: 1.) The stomach produces hydrochloric acid. Enzymes in the stomach work best in acidic conditions 2.) The liver produces bile which is stored in the gall bladder before being released into the small intestine. Bile neutralises the acid that was added to food in the stomach. This provides alkaline conditions in which enzymes in the small intestine work best at.

Making use of enzymes

Enzymes in industry Type of enzyme Proteases Carbohydrases Isomerases Use To ‘pre-digest’ protein in baby foods To turn starch into sugar syrup for making chocolates and cakes To turn glucose syrup into fructose syrup to use in slimming foods Why is it used? The baby may not be able to digest all the protein itself Sugar syrup is sweet and makes the food ‘taste nice’ Fructose is twice as sweet as glucose so it can be used in smaller amounts in slimming foods