VHH fragments (nanobodies) are the smallest natural antigen-binding domains, derived from camelid heavy-chain-only antibodies.

Size

~15 kDa (smallest)

Origin

Camelids (llamas, camels)

Stability

Exceptional heat/pH resistance

Format

Single domain, no light chain

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Unique Features

VHH can access cryptic epitopes in protein cavities that larger antibodies cannot reach.
  • Extended CDR3 loops - Longer than conventional antibodies
  • No light chain pairing - Functions independently
  • Refolding capability - Can refold after denaturation
Requires specialized discovery platforms (camelid immunization or synthetic libraries).

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