Small Molecule Binder Discovery Strategy

Small Molecule Binder Discovery Strategy

Systematic discovery of novel small molecule binders using 60+ ToolUniverse tools across druggability assessment, known ligand mining, similarity expansion, ADMET filtering, and synthesis feasibility.

LOOK UP DON'T GUESS - Always retrieve actual data from tools before drawing conclusions. Do not assume druggability, binding sites, or compound properties based on target class alone.

KEY PRINCIPLES:

1. Report-first approach - Create report file FIRST, then populate progressively
2. Target validation FIRST - Confirm druggability before compound searching
3. Multi-strategy approach - Combine structure-based and ligand-based methods
4. ADMET-aware filtering - Eliminate poor compounds early
5. Evidence grading - Grade candidates by supporting evidence
6. Actionable output - Provide prioritized candidates with rationale
7. English-first queries - Always use English terms in tool calls. Respond in the user's language

Binding Site Reasoning (Start Here)

Before any tool call, reason about the target's structural biology:

Is the binding site a well-defined pocket (small molecule accessible) or a flat protein-protein interface (needs peptide/macrocycle)? This determines your screening strategy.

• Enzymes with active sites (proteases, kinases, ATPases): deep, well-defined pockets. Classic small molecule territory. Prioritize co-crystal structure search and known inhibitor scaffold analysis.
• GPCRs and ion channels: transmembrane pockets. Structure often available; start with GPCRdb and GtoPdb for known pharmacology.
• Nuclear receptors: deep hydrophobic pockets. Excellent small molecule tractability; ligand-based methods are well-powered.
• Protein-protein interfaces: flat, large contact surface. Small molecules rarely compete effectively unless there is a "hot spot" cavity. Check whether any allosteric pockets exist before committing to small molecule strategy. Warn the user if no pocket is found. If the target is a known molecular-glue-degrader neosubstrate (or the goal is to induce a new PPI rather than block an existing pocket), check MolGlueDB_search_compounds/MolGlueDB_get_compound for known glue chemotypes before declaring the target undruggable by small molecules.
• Intrinsically disordered regions: essentially no direct small molecule approach. Redirect to peptide strategies, or check MolGlueDB_search_compounds in case the target is a documented molecular-glue neosubstrate.
• Scaffolding / adaptor proteins: assess co-crystal structures for unexpected pockets before declaring undruggable.

Use this reasoning to select phases and warn the user about challenges before executing a full workflow.

Critical Workflow Requirements

1. Report-First Approach (MANDATORY)

DO NOT show search process or tool outputs to the user. Instead: