Chemical Entity

When to use

• Find ChEBI IDs for chemical entities to use in GO term definitions
• Determine the correct protonation state for a chemical
• Understand chemical classification and parent classes
• Create biosynthetic process or metabolic process terms that reference chemicals
• Verify chemical cross-references

The general thing to keep in mind is that selecting the right CHEBI term is harder than it seems. Don't assume that the term with the most biologist-friendly label is the right one!

CRITICAL: Protonation State Selection (pH 7.3 Canonicalization)

For GO term logical definitions, ALWAYS prefer the major species at physiological pH (approximately 7.3).

• for chemicals with different protonation states, the ph7.3 form must be used
• for chemicals with different stereoisomers, the appropriate L or D form must be used (except in very rare cases where we want to be agnostic)

Exemplar term