Acid Phosphatase 5, Tartrate Resistant (ACP5)

is a glycosylated monomeric metalloenzyme expressed in mammals. It has a molecular weight of approximately 35kDa, a basic isoelectric point (7.6-9.5) , and optimal activity in acidic conditions. TRAP is synthesized as latent proenzyme and activated by proteolytic cleavage and reduction. It is differentiated by other mammalian acid phosphatases by its resistance to inhibition by tartrate, molecular weights and characteristic purple colour. The mechanism of phosphate ester hydrolysis by TRAP is through a nucleophilic attack mechanism, whereby, catalysis occurs with the binding of a phosphate-substrate to the Fe²⁺ in the active site of TRAP. This is then followed by a nucleophilic attack by a hydroxide ligand on the bound phosphorus atom, resulting in cleavage of the phosphate ester bond and production of an alcohol.