Which method allows design of a molecule to fit into the target's active site?

• A. Structure-based drug design
• B. Combinatorial Chemistry
• C. High-Throughput Screening
• D. Analogues of natural ligands

Answer: (A)

Designing a molecule to fit a target’s active site relies on knowing the three‑dimensional shape and chemical features of the site and then shaping a compound to make favorable contacts—hydrogen bonds, ionic interactions, and hydrophobic packing—so it adopts a conformation that precisely complements the pocket. This is structure-based drug design, where structural information guides the design and optimization of ligands, often using computer modeling, docking, and scoring to predict fit and affinity and then refining the molecule to improve potency and selectivity. It differs from approaches that don’t use the pocket geometry upfront: combinatorial chemistry builds vast libraries without focusing on exact fit; high-throughput screening screens many compounds to find hits without prior structural guidance; and modifying natural ligands relies on existing scaffolds rather than exploiting the unique features of the active site revealed by structure.