Enzymes and Digestion

Enzymes and Digestion

Basic Concepts of Enzymes

  • Enzymes are biological catalysts that speed up chemical reactions in living organisms.
  • They are proteins, made up of long chains of amino acids, and their structure determines their function.
  • Each enzyme is specific to one type of reaction due to its active site - a region where substrate molecules bind and react.

How Enzymes Work

  • Enzymes work on the model called the ‘lock and key’ principle. The substrate molecule fits perfectly into the active site of the enzyme, much like a key fits into a lock.
  • They catalyse reactions by lowering the activation energy, thus allowing reactions to occur faster.
  • At the end of the reaction, the substrate is converted into products and leaves the enzyme, which is then free to catalyse another reaction.

Factors Affecting Enzyme Activity

  • The rate of enzyme activity can be influenced by temperature, pH levels and substrate concentration.
  • Beyond an optimal temperature or pH, enzyme activity will decrease due to denaturation (loss of structure) of the enzyme.
  • If the substrate concentration is increased, the rate of reaction will increase until all enzyme active sites are occupied - this is called saturation.

Role of Enzymes in Digestion

  • Enzymes play a major part in the digestion system by breaking down complex food molecules into smaller, absorbable units.
  • Amylase, secreted in the mouth and pancreas, breaks down complex carbohydrates (starch) into simpler sugars.
  • Proteases, secreted in the stomach, pancreas and small intestine, break down proteins into amino acids.
  • Lipases, secreted in the pancreas and small intestine, break down fats into fatty acids and glycerol.

Enzyme Inhibitors

  • An enzyme inhibitor is a molecule that binds to an enzyme and decreases its activity.
  • There are two types of inhibitors: Competitive inhibitors, which compete with the substrate for the active site; and non-competitive inhibitors, which attach to an area other than the active site, causing the enzyme to change shape and making the active site less effective.

Remember, digestive enzymes are crucial components of good health, as they enable the body to obtain and absorb nutrients needed to maintain health and fight disease.