Unlike other S53 peptidases, it has steric constraints on the P4 substrate pocket, which might contribute to its preferential cleavage of tripeptides from the unsubstituted N-terminus of proteins.

The protease functions in the lysosome to cleave N-terminal tripeptides from substrates and has weaker endopeptidase activity.

Bi-allelic mutations of the gene TPP1 have been found to result in one of these disorders, called late-infantile neuronal ceroid lipofuscinosis, also known as CLN type 2 or Jansky–Bielschowsky disease.

[11] Mutations of gene is associated with the failure to degrade specific neuropeptides and a subunit of ATP synthase in the lysosome and accumulation of the fluorescent pigments.

[12] The disease causes childhood onset neurodegeneration resulting in epilepsy, movement disorders and progressive loss of motor and cognitive skills.