Describe the functions of enzymes as follows: (a) amylase breaks down starch to simple reducing sugars (b) proteases break down protein to amino acids (c) lipase breaks down fats and oils to fatty acids and glycerol

Enzymes are biological catalysts that facilitate chemical reactions in the body, including the digestion of macromolecules. Here’s a detailed description of the functions of three key digestive enzymes: amylase, proteases, and lipase.

Functions of Enzymes in Digestion

(a) Amylase: Breakdown of Starch to Simple Reducing Sugars

• Source: Amylase is produced in the salivary glands (salivary amylase) and the pancreas (pancreatic amylase).
• Function:
  • Substrate: Amylase acts on starch, a polysaccharide composed of long chains of glucose units.
  • Mechanism: It catalyzes the hydrolysis of starch into smaller carbohydrate molecules, such as maltose (a disaccharide) and eventually into glucose (a monosaccharide).
  • Importance: The breakdown of starch into simple sugars is essential for energy production. Glucose can be readily absorbed by the intestinal lining and utilized by cells for energy.

(b) Proteases: Breakdown of Protein to Amino Acids

• Source: Proteases are secreted by the stomach (e.g., pepsin) and the pancreas (e.g., trypsin and chymotrypsin).
• Function:
  • Substrate: Proteases target proteins, which are large polypeptides made up of amino acid chains.
  • Mechanism: These enzymes cleave peptide bonds between amino acids through hydrolysis, breaking proteins down into smaller peptides and ultimately into individual amino acids.
  • Importance: Amino acids are the building blocks of proteins and are crucial for various bodily functions, including tissue repair, enzyme production, hormone synthesis, and immune function.

(c) Lipase: Breakdown of Fats and Oils to Fatty Acids and Glycerol

• Source: Lipase is primarily produced by the pancreas and is also found in saliva (lingual lipase) and gastric juice.
• Function:
  • Substrate: Lipase acts on triglycerides, which are fats and oils composed of glycerol and three fatty acid chains.
  • Mechanism: It catalyzes the hydrolysis of triglycerides into free fatty acids and glycerol. This process is often aided by bile salts, which emulsify fats to increase the surface area for lipase action.
  • Importance: The breakdown products—fatty acids and glycerol—are essential for energy storage, cellular structure, hormone production, and absorption of fat-soluble vitamins (A, D, E, K).