Evaluation of protein binders as crystallization facilitators

High-resolution structures of proteins provide valuable
information for rational drug design. Prerequisite
to obtain such structures are well-ordered threedimensional
crystals. Some proteins have proven to be
very difficult or even impossible to crystallize, and for
such examples a number of ways have been developed
to improve the chances for successful crystallization.
Genetic engineering of the protein, either by the
introduction of surface mutations or by the variation
of the protein construct length, is often effective. Cocrystallization
of proteins with other proteins may be
a good alternative. Classically, antibodies or antibody
Fab-fragments which might stabilize the target protein
were used for co-crystallization and often result in an
improved overall crystal quality.