B2: Enzymes

Enzymes = protein molecules made up of long chains of amino acids

They are biological catalysts which increase the rate of chemical reactions

They are folded into complex shapes for substrate molecules to fit in to the activation site

if the shape of the activation site changes then the enzyme will no longer function properly and will become denatured

enzymes can become denatured by the wrong pH or high temperatures

• they help to speed up a reaction
• they can work at low temperatures which saves energy
• can immobilise enzymes in a material to make them more stable
• they can work at atmospheric pressures so equipment is not as complex or expensive
• they remain unchanged by the reaction so can be reused

• easily broken down by the wrong pH
• enzymes are specific - so different enzymes would be needed for different jobs
• soluble in water - can be difficult to seperate them from the products
• expensive to buy
• easily broken down by high temperatures

• catalyse processes such as respiration, photosynthesis and proteinsynthesis

• they catalyse reactions which build up amino acids and protein

The main group of enzymes outside body cells are the digestive enzymes.

The digestive enzymes:

• are produced by specialised cells in the glands
• pass out of cells into the gut
• catalyse the breakdown of large food molecules into smaller molecules

Amylase: Produced in the salivary glands, pancreas and small intestine. Turns starch to sugars.

Protease:Produced in the stomach, pancreas and small intestine.Turns proteins into amino acids.

Lipase: Produced in the pancreas and small intestine. Turns lipids into fatty acids and glycerol.

protease = used to pre-digest proteins in baby food

lipase = used in biological detergents with protease to break down stains into smaller substances

carbohydrase = used to convert starch syrup into sugar syrup which is more valuable and can be used in sports drinks

isomerase = converts glucose syrup into fructose syrup which is sweeter and can be used in smaller amounts. Perfect for slimming foods.

• produced in the liver
• stored in the gall bladder
• neutralises the acid which was added to food in the stomach
• provides alkaline conditions
• enzymes in the small intestine work more effectively in these conditions