title: Ser475, Glu272, Asp276, Asp327, and Asp360 are involved in catalytic activity of human tripeptidyl-peptidase I.
abstract: Tripeptidyl-peptidase I (TPP I) is a lysosomal aminopeptidase that sequentially removes tripeptides from small polypeptides and also shows a minor endoprotease activity. Mutations in TPP I are associated with a fatal lysosomal storage disorder--the classic late-infantile form of neuronal ceroid lipofuscinoses. In the present study, we analyzed the catalytic mechanism of the human enzyme by using a site-directed mutagenesis. We demonstrate that apart from previously identified Ser475 and Asp360, also Glu272, Asp276, and Asp327 are important for catalytic activity of the enzyme. Involvement of serine, glutamic acid, and aspartic acid in the catalytic reaction validates the idea, formulated on the basis of significant amino acid sequence homology and inhibition studies, that TPP I is the first mammalian representative of a growing family of serine-carboxyl peptidases.
authors.affiliation: Department of Developmental Neurobiology, The New York State Institute for Basic Research in Developmental Disabilities, 1050 Forest Hill Road, Staten Island, NY 10314, USA.
authors.forename: Mariusz
authors.initials: M
authors.lastname: Walus
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Kida
authors.forename: Krystyna E
authors.initials: KE
authors.lastname: Wisniewski
authors.forename: Adam A
authors.initials: AA
authors.lastname: Golabek
mesh_terms: D000595:Amino Acid Sequence; D000626:Aminopeptidases; D000818:Animals; D001224:Aspartic Acid / Q000235:genetics / Q000378:metabolism*; D016466:CHO Cells; D002384:Catalysis; D006224:Cricetinae; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; D010450:Endopeptidases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D018698:Glutamic Acid / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D016415:Sequence Alignment; D012694:Serine / Q000235:genetics / Q000378:metabolism*; D057057:Serine Proteases; D000091346:Tripeptidyl-Peptidase 1
chemical_list: D000091346:Tripeptidyl-Peptidase 1; D001224:Aspartic Acid; D018698:Glutamic Acid; D012694:Serine; D010450:Endopeptidases; D057057:Serine Proteases; D000626:Aminopeptidases; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; C000717267:TPP1 protein, human