The chelate effect in binding, catalysis, and chemotherapy

Cyclodextrin (CD) dimers bind amino acid side chains, and such binding can dissociate aggregated proteins, including citrate synthase (dimer) and lactic dehydrogenase (tetramer). A CD dimer can bind a hydrophobic photosensitizer that, upon irradiation, generates singlet oxygen. This cleaves the dimer and releases the photosensitizer. CD dimers in a cytochrome P-450 mimic steer catalyzed hydroxylation to a bound steroid with geometric control. Chelate binding has also led to a group of cytodifferentiating agents whose mechanism has been recently established. They have promising anticancer properties, and are currently entering human trials as therapeutic agents.