Digestive enzymes
The groups of enzymeA protein which catalyses or speeds up a chemical reaction. involved in the breakdown of food are:
carbohydraseEnzyme that breaks down carbohydrates. break down carbohydrates:
\(\mathbf{carbohydrate}\; \overset{\mathbf{carbohydrase}}{\rightarrow}\; \mathbf{simple\; sugars}\)
Starch is a type of carbohydrate. The carbohydrase that breaks down starch is amylaseAn enzyme that can break down starch into simple sugars.:
\(\mathbf{starch}\; \overset{\mathbf{amylase}}{\rightarrow}\; \mathbf{maltose}\)
proteaseEnzyme that breaks down proteins. break down proteins:
\(\mathbf{protein}\; \overset{\mathbf{protease}}{\rightarrow}\; \mathbf{amino\; acids}\)
lipaseEnzyme that breaks down lipids (fats and oils). break down lipidFat or oils, composed of fatty acids and glycerol.
\(\mathbf{lipid}\; \overset{\mathbf{lipase}}{\rightarrow}\; \mathbf{fatty\; acids}\;\mathbf{+\; glycerol}\)
Carbohydrases
Carbohydrases break down carbohydrates in several regions of the digestive system.
Most of the carbohydrate we eat is starch, so this will be the main substrateA substance on which enzymes act. in the early part of digestion for enzyme action.
| Region of digestive system | Enzyme | Where produced | Substrate | Broken down into |
| Mouth | Salivary amylase | Salivary glands | Starch | Maltose |
| Small intestine - Duodenum | Pancreatic amylase | Pancreas | Starch | Maltose |
| Small intestine - Ileum | Maltase | Wall of ileum | Maltose | Glucose |
| Region of digestive system | Mouth |
|---|---|
| Enzyme | Salivary amylase |
| Where produced | Salivary glands |
| Substrate | Starch |
| Broken down into | Maltose |
| Region of digestive system | Small intestine - Duodenum |
|---|---|
| Enzyme | Pancreatic amylase |
| Where produced | Pancreas |
| Substrate | Starch |
| Broken down into | Maltose |
| Region of digestive system | Small intestine - Ileum |
|---|---|
| Enzyme | Maltase |
| Where produced | Wall of ileum |
| Substrate | Maltose |
| Broken down into | Glucose |
Proteases
Proteases break down proteins in several regions of the digestive system.
| Region of digestive system | Enzyme | Where produced | Substrate | Broken down into |
| Stomach | Protease - pepsin | Gastric glands in stomach | Proteins | Begins the breakdown into amino acids |
| Small intestine - Duodenum | Protease - trypsin | Pancreas | Proteins | Continues the breakdown into amino acids |
| Small intestine - Ileum | Protease - peptidase | Wall of ileum | Peptides | Completes the breakdown into amino acids |
| Region of digestive system | Stomach |
|---|---|
| Enzyme | Protease - pepsin |
| Where produced | Gastric glands in stomach |
| Substrate | Proteins |
| Broken down into | Begins the breakdown into amino acids |
| Region of digestive system | Small intestine - Duodenum |
|---|---|
| Enzyme | Protease - trypsin |
| Where produced | Pancreas |
| Substrate | Proteins |
| Broken down into | Continues the breakdown into amino acids |
| Region of digestive system | Small intestine - Ileum |
|---|---|
| Enzyme | Protease - peptidase |
| Where produced | Wall of ileum |
| Substrate | Peptides |
| Broken down into | Completes the breakdown into amino acids |
Lipases
Lipases break down lipids in one region of the digestive system.
| Region of digestive system | Enzyme | Where produced | Substrate | Broken down into |
| Small intestine - Duodenum | Lipase | Pancreas | Lipids | Fatty acids and glycerol |
| Region of digestive system | Small intestine - Duodenum |
|---|---|
| Enzyme | Lipase |
| Where produced | Pancreas |
| Substrate | Lipids |
| Broken down into | Fatty acids and glycerol |
