Enzymes

• Catalysts are substances that speed up a chemical reaction without being chemicaly changed
• An enzyme is a protein and is a biological catalyst. It alters chemical reactions. It also remains chemically unchanged at the end of a reaction.
• Activation energy is the energy needed to start a chemical reaction. It is the minimum energy required to start a reaction.
• Digestive enzymes

  • Amylase
  • Maltase
  • Protease
  • Lipase
• Enzymes can catalyse the building up of complex substances and the breaking down of complex substances which are known as Anabolic and Catabolic respectively.
• Enzymes speed up chemical reactions, they are required in minute amounts, they are highly specific in action
• Lock and Key Hypothesis

  Enzyme is the lock

  Substrate is the key
• Enzymes have a specific 3-D shape that has an active site. ONLY a substrate with a complementary shape to that of that active site can fit into the active site to form an enzyme substrate complex.
• Once the substrate attaches to the active site, the products are formed and then released from the active site. The enzyme remains unchanged
• Enzyme denaturation is the change of shape of an enzyme due to heat or pH which can change the function of the enzyme.
• When the enzyme is denatured, there is a loss or change in the active site.
• Enzymes are inactive at low temperatures and active at high temperatures.
• The optimum temperature is the temperature when the rate of reaction is at its maximum and the enzyme is most active. The optimum temperature for most enzymes is 40-45 degrees Celsius
• After optimum temperature the formation of ES complex reduces. At a high temperature the bond within the enzyme is broken resulting in a change in the shape of the enzyme and its active site
• Different enzymes have different optimum Ph Levels. An extreme change in Ph causes denaturation.