title: The substrate range of tripeptidyl-peptidase I.
abstract: Tripeptidyl-peptidase I (TPP-I) is an exopeptidase which removes tripeptides from the N-terminus of peptides. Mutations in TPP-I are responsible for late infantile neuronal ceroid lipofuscinosis (CLN2). The nature of the physiological substrates and the range and specificity of the enzyme are unclear. Previous experiments suggest that the enzyme can degrade small peptides but not proteins. Digestion of a range of peptides of different size by TTP-I suggests that the enzyme will degrade small peptides with an extended N-terminal domain but not structured peptides. In general, this cut-off occurs between masses of 4.5 kDa and 6 kDa. Reference to the structures of other peptidases suggests a mechanism for this size selectivity.
authors.affiliation: Department of Histopathology, St George's Hospital Medical School, Cranmer Terrace, London SW17 0RE, UK.
authors.forename: F
authors.initials: F
authors.lastname: Bernardini
authors.forename: M J
authors.initials: MJ
authors.lastname: Warburton
mesh_terms: D000626:Aminopeptidases; D001665:Binding Sites; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; D010450:Endopeptidases / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D007223:Infant; D008970:Molecular Weight; D009472:Neuronal Ceroid-Lipofuscinoses / Q000201:enzymology*; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D057057:Serine Proteases; D013379:Substrate Specificity; D000091346:Tripeptidyl-Peptidase 1
chemical_list: D010446:Peptide Fragments; D000091346:Tripeptidyl-Peptidase 1; D010450:Endopeptidases; D057057:Serine Proteases; D000626:Aminopeptidases; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; C000717267:TPP1 protein, human