Specificity of an enzyme

• Definition of an enzyme

  Enzyme is a protein (biocatalyst) that accelerates the hydrolysis of complex food into simpler ones.

  It is used in low amounts and remains unchanged (active) at the end of the reaction.
• Properties of an enzyme

  1. Each enzyme acts on a specific substrate.
  2. Each enzyme acts on a specific temperature.
  3. Each enzyme acts on a specific pH(medium).
  4. Each enzyme acts on a specific duration.
• Salivary amylase


  It is an enzyme found in saliva secreted by salivary gland acts on cooked starch and transforms it into maltose.
• Favorable conditions of salivary amylase

  • Substrate: Cooked starch
  • Temperature: 37C
  • pH: Neutral medium (pH=7)
  • Duration: 15-20mins
• Pepsin


  It is an enzyme found in the gastric juice in the stomach. It acts on protein and digests it into peptide.
• Favorable conditions for pepsin

  • Substrate: protein
  • Temperature: 37C
  • pH: Acidic medium (pH<7)
  • Duration: 1hour
• Definition of Trypsin

  It is an enzyme found in pancreatic juice secreted by pancreas in the small intestine that acts on protein and digests it into amino acids.
• favorable conditions for trypsin

  • Substrate: protein
  • Temperature: 37C
  • pH: basic medium (pH=8>7)
  • Duration: 1hour
• Lipase

  It is an enzyme found in the pancreatic juice acts on lipids and transforms them into fatty acids and glycerol.
• Favorable conditions for lipase

  • Substrate: lipids
  • Temperature: 37C
  • pH: basic medium (pH=8>8)
  • Duration: 3hours
• Maltase


  It is an enzyme found in the intestinal juice acts on maltose and transforms it into glucose.
• Lactase

  acts on lactose and hydrolyzes it into glucose and galactose.
• Sucrase

  acts on sucrose and digests it into glucose and fructose