Activated macrophages expressing inducible nitric oxide synthase generate nitric oxide from arginine. The chief microbicidal mechanism attributable to this radical is:

• A Reaction with superoxide yielding peroxynitrite that damages microbial DNA and proteins ✓
• B Direct halogenation of microbial cell wall lipids
• C Formation of pores in microbial membranes by polymerization into amyloid fibrils
• D Competitive inhibition of bacterial folate synthesis enzymes

Explanation

Nitric oxide combines spontaneously with superoxide generated by the phagocyte NADPH oxidase to form peroxynitrite, a highly reactive nitrogen species that nitrates tyrosine residues and damages microbial DNA, lipids, and proteins. Halogenation of microbes is performed by myeloperoxidase using chloride ions, and folate antagonism describes sulfonamide antibiotics, neither of which involves nitric oxide chemistry.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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