Enzymes

The shape of an enzyme is vital for the enzyme’s function. High temperatures change the shape.   Different enzymes work best at different pH values.   Some enzymes work outside the body cells. The digestive enzymes are produced by specialised cells in glands and in the lining of the gut. The enzymes then pass out of the cells into the gut where they come into contact with food molecules. They catalyse the breakdown of large molecules into smaller molecules

The enzyme amylase is produced in the salivary glands, the pancreas and the small intestine. This enzyme catalyses the breakdown of starch into sugars in the mouth and small intestine.   Protease enzymes are produced by the stomach, the pancreas and the small intestine. These enzymes catalyse the breakdown of proteins into amino acids in the stomach and the small intestine. Lipase enzymes are produced by the pancreas and small intestine. These enzymes catalyse the breakdown of lipids (fats and oils) into fatty acids and glycerol in the small intestine.

The stomach also produces hydrochloric acid. The enzymes in the stomach work most effectively in these acid conditions.   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 most effectively.

Some microorganisms produce enzymes that pass out of the cells. These enzymes have many uses in the home and in industry.   In the home:   ■ Biological detergents may contain protein-digesting and fat-digesting enzymes (proteases and lipases)   ■ Biological detergents are more effective at low temperatures than other types of detergents.   In industry:   ■ proteases are used to ‘pre-digest’ the protein in some baby foods   ■ Carbohydrases are used to convert starch into sugar syrup   ■ Isomerase is used to convert glucose syrup into fructose syrup, which is much sweeter and therefore can be used in smaller quantities in slimming foods.

Enzymes in IndustryIn industry, enzymes are used to bring about reactions at normal temperatures and pressures that would otherwise require expensive, energy-demanding equipment. However, most enzymes are denatured at high temperatures and many are costly to produce.   Suggested ideas for practical work to develop skills and understanding include the following:   ■ design an investigation to find the optimum temperature for biological and non-biological washing powders to remove stains from cotton and other materials   ■ investigate the action of enzymes using catalase at different concentrations and measuring the rate at which oxygen is given off from different foods, eg liver, potato, celery and apple   ■ plan and carry out an investigation into enzyme action using the reaction between starch and amylase at different temperatures, pH and concentrations  ■ using small pieces of cooked sausage, use 2% pepsin and 0.01M HCl in water baths at different temperatures to estimate the rate of digestion. This can also be carried out with 2% trypsin and 0.1M NaOH. The concentration of both enzymes can be varied  ■ using computer simulations of enzymes to model their action in varying conditions of pH, temperature and concentration.

Type of EnzymesThe enzyme amylase is produced in the salivary glands, the pancreas and the small intestine. This enzyme catalyses the breakdown of starch into sugars in the mouth and small intestine.  Protease enzymes are produced by the stomach, the pancreas and the small intestine. These enzymes catalyse the breakdown of proteins into amino acids in the stomach and the small intestine. Lipase enzymes are produced by the pancreas and small intestine. These enzymes catalyse the breakdown of lipids (fats and oils) into fatty acids and glycerol in the small intestine.

Enzymes and OrgansThe enzyme amylase is produced in the salivary glands, the pancreas and the small intestine. This enzyme catalyses the breakdown of starch into sugars in the mouth and small intestine.   Protease enzymes are produced by the stomach, the pancreas and the small intestine. These enzymes catalyse the breakdown of proteins into amino acids in the stomach and the small intestine. Lipase enzymes are produced by the pancreas and small intestine. These enzymes catalyse the breakdown of lipids (fats and oils) into fatty acids and glycerol in the small intestine.

Enzymes at HomeSome microorganisms produce enzymes that pass out of the cells. These enzymes have many uses in the home and in industry.   In the home:   ■ Biological detergents may contain protein-digesting and fat-digesting enzymes (proteases and lipases)   ■ Biological detergents are more effective at low temperatures than other types of detergents.   In industry:   ■ proteases are used to ‘pre-digest’ the protein in some baby foods   ■ Carbohydrases are used to convert starch into sugar syrup   ■ Isomerase is used to convert glucose syrup into fructose syrup, which is much sweeter and therefore can be used in smaller quantities in slimming foods. 

Enzymes in IndustryIn industry, enzymes are used to bring about reactions at normal temperatures and pressures that would otherwise require expensive, energy-demanding equipment. However, most enzymes are denatured at high temperatures and many are costly to produce.   Suggested ideas for practical work to develop skills and understanding include the following:   ■ design an investigation to find the optimum temperature for biological and non-biological washing powders to remove stains from cotton and other materials   ■ investigate the action of enzymes using catalase at different concentrations and measuring the rate at which oxygen is given off from different foods, eg liver, potato, celery and apple   ■ plan and carry out an investigation into enzyme action using the reaction between starch and amylase at different temperatures, pH and concentrations  ■ using small pieces of cooked sausage, use 2% pepsin and 0.01M HCl in water baths at different temperatures to estimate the rate of digestion. This can also be carried out with 2% trypsin and 0.1M NaOH. The concentration of both enzymes can be varied  ■ using computer simulations of enzymes to model their action in varying conditions of pH, temperature and concentration. 

Enzymes

Types of Enzymes

Enzymes and Organs

Enzymes at Home

Enzymes in Industry