80. The breakdown of protein is facilitated by which enzyme?

Appeared in: JSSH Staff Nurse - 2019

Explanation

Trypsin is a powerful proteolytic enzyme, also known as a protease, whose primary function is to digest proteins.
It is produced by the pancreas as an inactive precursor, trypsinogen, and is secreted into the small intestine.
In the duodenum, trypsinogen is converted to its active form, trypsin, by the enzyme enteropeptidase (enterokinase).
Trypsin then breaks down large protein molecules into smaller fragments called peptides by hydrolyzing peptide bonds.

Option B: Lactase is a carbohydrase, not a protease. Its function is to break down lactose, the sugar found in milk, into glucose and galactose.
Option C: Amylase is a carbohydrase that digests complex carbohydrates (starches). Pancreatic and salivary amylase break down starch into simpler sugars like maltose.
Option D: Sucrase is a carbohydrase located in the brush border of the small intestine. It breaks down sucrose (common table sugar) into glucose and fructose.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Enzymatic digestion of macronutrients as background academic context rather than a clinical decision trigger.
A deficiency in pancreatic enzymes, including trypsin, can occur in conditions like pancreatitis or cystic fibrosis, leading to malabsorption of proteins, malnutrition, and steatorrhea (fatty stools).
Enzyme replacement therapy, which includes proteases, is a key treatment for pancreatic insufficiency.
What if? If a patient has acute pancreatitis, the premature activation of trypsinogen to trypsin within the pancreas can cause autodigestion of the pancreatic tissue, a painful and life-threatening condition.

How to Approach the Question

First, identify the key term in the question stem, which is 'protein'.
The question asks for the enzyme responsible for the 'breakdown of protein'. This requires knowledge of digestive enzymes.
Recall the three main classes of macronutrients: proteins, carbohydrates, and fats, and the general enzyme classes that digest them (proteases, carbohydrases, lipases).
Evaluate each option: Trypsin is a known protease. Lactase, Amylase, and Sucrase are all related to sugar/carbohydrate digestion.
Match the substrate 'protein' with the correct enzyme class 'protease'.
Select Trypsin as it is the only protease among the options provided.

Concept Tested & Keywords

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E6 Textbook of Biochemistry for medical StudentsDM Vasudevan Part 1 (pp 26-370 of 370) p. 273-275

E6 Harper's Illustrated Biochemistry2023 (pp 26-793 of 813) p. 513-515

E6 Physiology Guyton 4SAE Part 2A p. 197-199

Practise the full JSSH Staff Nurse - 2019

Attempt every question from this paper in a timed mock, then review the full solution for each one.