The first activation study of a η-class carbonic anhydrase (CAs, EC 4.2.1.1) is reported. A panel of 24 natural and non-natural amino acids and amines was used to explore the activation profile of Plasmodium falciparum CA (PfACA). The most effective activators belonged to the amino acid chemotype, with d-Glu, l-Asp, l-/d-Phe and l-/d-DOPA possessing activation constant in the range of 82 nM-0.75 µM, whereas l-/d-His, l-Tyr, 4-amino-l-Phe and l-Gln were slightly less effective (KA in the range of 1.00-2.51 µM. The only amine with submicromolar activating properties was 1-(2-aminoethyl-piperazine) with a KA of 0.71 µM, whereas histamine, dopamine and serotonin showed KA ranging between 7.18 and 9.97 µM. As CA activators have scarcely been investigated for their interaction with protozoan CAs, this study may be relevant for an improved understanding of the role of this enzyme in the life cycle of the malaria producing organisms belonging to the genus Plasmodium.
