As a member of the MH clan in the M18 family of zinc metallopeptidase 2 molecules Aspartyl aminopeptidase is part of the basic protein degrading machinery of the cell. It cleaves Glutamyl or Aspartyl residues from the unblocked N-terminus of the cell and is distinct from Glu aminopeptidase by having a preference for Asp residues. This protein in Peudomonas Aeruginosa has a dodecameric tetrahedral structure similar to that of glutamyl aminopeptidase in Pyrococcus horikoshii. It cleaves unblocked residues by allowing only unfolded proteins to pass through channels in the face of the tetrahedral structure to interact with the zinc catalytic centre. This protein has a high sequence conservation between broad classes of organisms, evolution mechanism is considered to be laterally transferred and is expressed at fairly even levels throughout mammalian tissues >0.1% confirming its importance as a basic metabolic cellular protein.