caa a22 4500 475744527 CHVBK 20180406123509.0 cr unu---uuuuu 170329e20000701xx s 000 0 eng 10.1023/A:1026432402259 doi (NATIONALLICENCE)springer-10.1023/A:1026432402259 α1-Antichymotrypsin and Kallistatin Hydrolysis by Human Cathepsin D [Elektronische Daten] [Daniel Pimenta, Vincent Chen, Julie Chao, Maria Juliano, Luiz Juliano] In the present paper, we demonstrate that α1-antichymotrypsin, a serpin with high inhibitory specificity toward cathepsin G, and kallistatin, a human serpin with high specificity toward tissue kallikrein, are digested by cathepsin D. α1-Antichymotrypsin was hydrolyzed essentially in the reactive center loop at L-S, A-L, or L-V bonds; kallistatin was split into small fragments, but we detected the cleavage at F-F and F-S bonds in its reactive center loop in the first 15 min of digestion. In contrast to α1-antichymotrypsin, kallistatin is irreversibly inactivated at pH 4.0. Synthetic internally quenched fluorescent peptides containing sequences similar to the reactive center loops of these serpins were hydrolyzed by cathepsin D. The peptides derived from kallistatin were hydrolyzed more efficiently, and particularly relevant was the high susceptibility of the substrates Abz-AIKFFSAQT-NRHILRFNRQ-EDDnp (K m = 0.08 μM, k cat = 2.4 s−1) and Abz-AIKFFSAQTNRQ-EDDnp (K m = 0.8 μM, k cat = 17.8 s−1), which were hydrolyzed at the F-F bond. Therefore, besides the description of a new class of very efficient internally quenched substrates for cathepsin D, we give evidence for the downregulation role of this proteinase on α1-antichymotrypsin and kallistatin. The acidification of extracellular milieu by tumor cells can result in activation of cathepsin D; as a consequence, kinins can be released, improving blood supply and leaving more cathepsin G available for the degradation of extracellular matrix. Plenum Publishing Corporation, 2000 Cathepsin D nationallicence kallistatin nationallicence antichymotrypsin nationallicence serpin nationallicence fluorogenic substrates nationallicence Pimenta Daniel Department of Biophysics, Escola Paulista de Medicina, 04044-020, São Paulo, SP, Brazil aut Chen Vincent Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 29425, Charleston, South Carolina aut Chao Julie Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 29425, Charleston, South Carolina aut Juliano Maria Department of Biophysics, Escola Paulista de Medicina, 04044-020, São Paulo, SP, Brazil aut Juliano Luiz Department of Biophysics, Escola Paulista de Medicina, 04044-020, São Paulo, SP, Brazil aut Journal of Protein Chemistry Kluwer Academic Publishers-Plenum Publishers 19/5(2000-07-01), 411-418 0277-8033 19:5<411 2000 19 10930 https://doi.org/10.1023/A:1026432402259 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1026432402259 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Pimenta Daniel Department of Biophysics, Escola Paulista de Medicina, 04044-020, São Paulo, SP, Brazil aut NATIONALLICENCE 700 1- Chen Vincent Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 29425, Charleston, South Carolina aut NATIONALLICENCE 700 1- Chao Julie Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 29425, Charleston, South Carolina aut NATIONALLICENCE 700 1- Juliano Maria Department of Biophysics, Escola Paulista de Medicina, 04044-020, São Paulo, SP, Brazil aut NATIONALLICENCE 700 1- Juliano Luiz Department of Biophysics, Escola Paulista de Medicina, 04044-020, São Paulo, SP, Brazil aut NATIONALLICENCE 773 0- Journal of Protein Chemistry Kluwer Academic Publishers-Plenum Publishers 19/5(2000-07-01), 411-418 0277-8033 19:5<411 2000 19 10930 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer