In 1993, scientists at the Vrije Universiteit Brussel discovered the occurence of bona fide antibodies devoid of light chains in Camelidae. The small and rigid recombinant antigen binding fragments (15kD) of these heavy chain only antibodies - known as V_HHs or Nanobodies^TM - proved to be unique research tools in structural biology.

By rigidifying flexible regions and obscuring aggregative surfaces, Xaperone^TM complexes warrant conformationally uniform samples that are key to protein structure determination by X-ray crystallography. The elucidation of the first GPCR structure in its active state using conformationally selective Xaperones demonstrates the power of the Xaperone platform to speed up and reduce the cost of generating diffracting quality crystals of challenging targets. Xaperones are antigen binding fragments from heavy chain only antibodies that:

• bind cryptic epitopes and lock proteins in unique native conformations
• increase the stability of soluble proteins and solubilized membrane proteins
• reduce the conformational complexity of soluble proteins and solubilized membrane proteins
• increase the polar surface enabling the growth of diffracting crystals
• allow to affinity-trap active protein