Enzyme needed in leucocytes for production of hypochlorite ?
**Core Concept**
The production of hypochlorite in leucocytes is a crucial step in the defense against pathogens, particularly in the context of the respiratory burst. This process involves the generation of reactive oxygen species (ROS) through the action of specific enzymes. The enzyme responsible for this process is a key component of the phagocytic cell's arsenal, enabling the destruction of ingested pathogens.
**Why the Correct Answer is Right**
The enzyme needed in leucocytes for the production of hypochlorite is myeloperoxidase. This enzyme catalyzes the conversion of hydrogen peroxide (H2O2) to hypochlorous acid (HOCl), a potent antimicrobial agent. Myeloperoxidase is primarily found in neutrophils, where it plays a vital role in the respiratory burst, facilitating the killing of pathogens. The enzyme's activity is crucial in the phagocytic cell's ability to combat infections.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because lactoperoxidase is a different enzyme, primarily found in the lactating mammary gland, and is not involved in the production of hypochlorite in leucocytes.
* **Option B:** This option is incorrect because catalase is an enzyme that catalyzes the decomposition of hydrogen peroxide to water and oxygen, rather than its conversion to hypochlorite.
* **Option C:** This option is incorrect because superoxide dismutase is an enzyme involved in the dismutation of superoxide (O2-) to hydrogen peroxide (H2O2), which is then converted to hypochlorite by myeloperoxidase.
**Clinical Pearl / High-Yield Fact**
Myeloperoxidase is a key enzyme in the neutrophil's ability to kill pathogens, and its deficiency can lead to increased susceptibility to infections. Deficiency of myeloperoxidase is associated with chronic granulomatous disease (CGD), a condition characterized by recurrent infections and granuloma formation.
**Correct Answer:** D.