Plasmepsins are a class of aspartic proteinases produced by the plasmodium parasite.
The family contains a group of aspartic proteinases homologous to plasmepsin 5. Plasmepsins are a class of at least 10 enzymes produced by the plasmodium parasite. Through their haemoglobin-degrading activity, they are an important cause of symptoms in malaria sufferers. This family of enzymes is a potential target for anti-malarial drugs. Plasmepsins are aspartic acid proteases, which means their active site contains two aspartic acid residues. These two aspartic acid residue act respectively as proton donor and proton acceptor, catalyzing the hydrolysis of peptide bond in proteins. Aspartic proteinases are composed of two structurally similar beta barrel lobes, each lobe contributing an aspartic acid residue to form a catalytic dyad that acts to cleave the substrate peptide bond. The catalytic Asp residues are contained in an Asp-Thr-Gly-Ser/thr motif in both N- and C-terminal lobes of the enzyme. There are four types of plasmepsins, closely related but varying in the specificity of cleavage site. The name plasmepsin may come from plasmodium (the organism) and pepsin (a common aspartic acid protease with similar molecular structure). This family of aspartate proteases is classified by MEROPS as the peptidase family A1 (pepsin A, clan AA).