A bacteriocidal enzyme found in nasal, intestinal secretion is?

RUHS, Jaipur, PB B.Sc Nursing Entrance-2019

Biochemistry & Nutrition

Easy

Appeared in: RUHS, Jaipur, PB B.Sc Nursing Entrance-2019

Explanation

Lysozyme is a key enzyme of the innate immune system, found in various bodily secretions like tears, saliva, nasal mucus, and intestinal fluids.
It exhibits bactericidal (bacteria-killing) activity by targeting and hydrolyzing the peptidoglycan layer, a major component of bacterial cell walls.
This enzymatic action, as described in pathology texts, involves breaking the muramic acid-N-acetylglucosamine bond in the glycopeptide coat of bacteria, which is particularly effective against Gram-positive bacteria.

Option B: Properdin is a plasma protein, not an enzyme found in mucosal secretions. Its role is within the systemic complement system in the blood.
Option C: Beta-lysine is released by platelets into the blood serum during coagulation. It is not a component of nasal or intestinal secretions.
Option D: Polypeptides is a very general chemical class. While some antimicrobial polypeptides (like defensins) exist in secretions, Lysozyme is the specific enzyme that fits the description, making it the best answer.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Innate immunity and biochemical barriers at mucosal surfaces as background academic context rather than a clinical decision trigger.
Understanding the role of lysozyme reinforces the importance of the body's first line of defense. Nurses can educate patients on practices that support mucosal health.
Maintaining adequate hydration and providing gentle oral and nasal care are crucial nursing interventions that help preserve the integrity of mucosal surfaces and the function of their antimicrobial components like lysozyme.
What if? If a patient has Sjögren's syndrome, an autoimmune condition causing severe dryness of the mouth and eyes, their reduced secretion of saliva and tears leads to lower levels of lysozyme. This significantly increases their risk for dental caries, oral candidiasis, and bacterial conjunctivitis, highlighting the protective role of this enzyme.

How to Approach the Question

First, identify the key terms in the question: 'bacteriocidal enzyme', 'nasal secretion', and 'intestinal secretion'. This directs you to think about the innate immune system's chemical barriers at mucosal surfaces.
Evaluate each option based on its known biological location and function.
Recall that Lysozyme is a classic example of an antimicrobial enzyme found in bodily fluids.
Analyze the distractors: Properdin is part of the blood's complement system, Beta-lysine is from platelets in the blood, and 'Polypeptides' is a general category, not a specific enzyme.
Conclude that Lysozyme is the most specific and accurate answer that fits all criteria of the question.

Concept Tested & Keywords

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E6 Pathology- ROBBINS & COTRAN PATHOLOGIC BASIS OF DISEASE 10TH Ed p. 92-94