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The defect of TPP Ⅰ causes a disease, late infantile neuronal ceroid lipofuscinosis(LINCL, CLN2). To investigate the bio-activity of tripeptidyl peptidase Ⅰ(TPP Ⅰ) from rat kidneys, the effects of digestion of angiotensin Ⅱ(Ang Ⅱ) and a synthetic endo-type substrate(Gly 1 -Lys-Pro-Iie-Pro 5 -Phe-Phe-Arg-Leu-Lys 10 ) via TPP Ⅰ were analyzed by HPLC and TOF-MS. The data suggest that the degradation rate of Ang Ⅱ can reach 18.2% by the rat TPP Ⅰ and DRV(Asp-Arg-Val) can be released from N-termini of Ang Ⅱ within 16 h. In addition, the synthetic endo-type substrate is cleaved at the same position between Phe 6 and Phe 7 . Accordingly, TPP Ⅰ shows two kinds of peptidase activities. One is a tripeptidyl peptidase activity and the other is a pepstatin insensitive carboxyl endopeptidase activity. Tripeptidyl peptidase activity and pepstatin insensitive carboxyl endopeptidase activity seem to be dual phases of one enzyme, TPP Ⅰ.
The investigation of bio-activity of tripeptidyl peptidase I (TPP I) from rat kidneys, the effects of digestion of angiotensin II (Ang II) and a synthetic endo-type substrate (Gly 1 -Lys-Pro-Iie-Pro 5 -Phe-Phe-Arg-Leu-Lys 10) via TPP Ⅰ were analyzed by HPLC and TOF-MS. The data suggest that the degradation rate of Ang Ⅱ can reach 18.2% by the rat TPP Ⅰ and DRV (Asp-Arg-Val) be released from N-termini of Ang Ⅱ within 16 h. In addition, the synthetic endo-type substrate is cleaved at the same position between Phe 6 and Phe 7. Tripeptidyl peptidase activity and pepstatin insensitive carboxyl endopeptidase activity seem to be two phases of one enzyme, TPP Ⅰ.