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Tripeptidyl‐peptidase I deficiency in classical late‐infantile neuronal ceroid lipofuscinosis brain tissue. Evidence for defective peptidase rather than proteinase activity
Author(s) -
Warburton M. J.,
Bernardini F.
Publication year - 2000
Publication title -
journal of inherited metabolic disease
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.462
H-Index - 102
eISSN - 1573-2665
pISSN - 0141-8955
DOI - 10.1023/a:1005665732189
Subject(s) - pepstatin , neuronal ceroid lipofuscinosis , batten disease , biochemistry , enzyme , proteolytic enzymes , biology , mucolipidosis , leupeptin , lysosomal storage disease , chemistry , protease , gene
Brain tissue from patients with classical late‐infantile neuronal ceroid lipofuscinosis (LINCL, an infantile form of Batten disease) is deficient in the lysosomal enzyme tripeptidyl‐peptidase I (EC 3.4.14.9). The activities of other lysosomal enzymes are either increased or decreased. Tripeptidyl‐peptidase I is a pepstatin‐insensitive exo‐tripeptidase, with little or no endo‐proteolytic activity, that is active on small peptides but not on large proteins. Using haemoglobin and casein as substrates for proteolytic activity, we were unable to demonstrate any significant defect in pepstatin‐sensitive or pepstatin‐insensitive proteinase activity in brain tissue or cultured skin fibroblasts of LINCL patients. These observations suggest that the lysosomal storage of undegraded, small peptides in LINCL results from the absence of peptidase rather than proteinase activity.