Acid (Asp/Glu) proteases

Aspartate proteases in viruses act in the processing of polyproteins whereas glutamic proteases are involved in virion maturation. They are a type of enzyme that catalyze the hydrolysis of peptide bonds and use a aspartate or glutamic residue in their active site. (Wikipedia)


Enzymatic reaction:

  • Asp-endopeptidase EC.3.4.23.-
  • Glu-endopeptidase EC.3.4.23.-

Mechanism These proteases are characterized by a conserved motif known as a catalytic dyad consisting of two aspartic acid residues or one glutamic and one aspartic acid residues. One carboxylate groups of these two acid residues assist in proton transfers from a water molecule that acts as the nucleophile, to attack the peptide bond of the peptide or protein to be cleaved. A well-known example of an aspartate protease is pepsin, which is found in the stomach and plays a crucial role in the digestion of proteins.


GenomeOrderFamilyFunctionTypeMEROPS familyDistribution (low incidence)Clan (fold)InterproUniProt exemplar
RtRNA Ortervirales imageimage Retroviridae, Orthoretrovirinae Virion maturation Aspartyl Peptidase A2 Virus, (animals, plant, fungi, protozoa) AA (pepsin fold)
IPR001969 Gag polyprotein
RtRNA Ortervirales imageimage Retroviridae, Spumaretrovirinae Virion maturation Aspartyl Peptidase A9 Virus, animals, fungi AA (pepsin fold)
IPR001641 Pro-pol polyprotein
RtRNA Ortervirales imageimage Caulimoviridae Virion maturation Aspartyl Peptidase A3 Virus, (plant) AA (pepsin fold)
IPR000588 Polyprotein
dsDNA Caudovirales image Salasmaviridae Self cleaving, Virion maturation Glutamine Peptidase G2 Bacteria, virus GB
IPR021865 Pre-neck appendage protein
dsDNA Algavirales image Phycodnaviridae Self cleaving, Virion maturation Glutamine Peptidase G2 Bacteria, virus GB
IPR021865 Chlorovirus glycoprotein repeat domain-containing protein