caa a22 4500 475744012 CHVBK 20180406123507.0 cr unu---uuuuu 170329e20000801xx s 000 0 eng 10.1023/A:1026505616359 doi (NATIONALLICENCE)springer-10.1023/A:1026505616359 Effects of Denaturing and Stabilizing Agents on the Inhibitory Activity and Conformational Stability of Schizolobium parahyba Chymotrypsin Inhibitor [Elektronische Daten] [Elizabeth de Souza, Rozeni Teles, Egle de A. Siqueira, Sonia de Freitas] The conformational stability of the Schizolobium parahyba chymotrypsin inhibitor (SPCI) was investigated based on conformational changes and inhibitory activity in the presence of chaotropic and stabilizing agents. At 90°C, the half-lifetime of SPCI was 154 min, while in the presence of 1 M KCl and 20% PEG 20,000, it was drastically reduced to 6 and 3 min, respectively. In contrast, at 90°C, the SPCI structure remained unaltered with the addition of 1 mM DTT and 56% glycerol. The reduction of the two disulfide bonds caused conformational changes in the SPCI without altering the inhibitory activity, suggesting that disulfide bonds are irrelevant to the maintenance of SPCI conformation. Unfolded structures were formed in the presence of 6 M GdnHCl, while in the presence of 8 M urea, destabilization was due to peptide bond rupture. These results suggest that the thermal inactivation of SPCI involves conformational changes and that hydrophobic and electrostatic interactions play a significant role, while the disulfide bonds are of secondary importance in maintaining the high thermal stability of SPCI. Plenum Publishing Corporation, 2000 Protease inhibitor nationallicence chymotrypsin inhibitor nationallicence Schizolobium parahyba nationallicence thermostability nationallicence Kunitz inhibitor nationallicence de Souza Elizabeth Department of Cellular Biology, Universidade de Brasilia, 70910-900, Brasilia-DF, Brazil aut Teles Rozeni Department of Cellular Biology, Universidade de Brasilia, 70910-900, Brasilia-DF, Brazil aut de A. Siqueira Egle Department of Cellular Biology, Universidade de Brasilia, 70910-900, Brasilia-DF, Brazil aut de Freitas Sonia Department of Cellular Biology, Universidade de Brasilia, 70910-900, Brasilia-DF, Brazil aut Journal of Protein Chemistry Kluwer Academic Publishers-Plenum Publishers 19/6(2000-08-01), 507-513 0277-8033 19:6<507 2000 19 10930 https://doi.org/10.1023/A:1026505616359 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1026505616359 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- de Souza Elizabeth Department of Cellular Biology, Universidade de Brasilia, 70910-900, Brasilia-DF, Brazil aut NATIONALLICENCE 700 1- Teles Rozeni Department of Cellular Biology, Universidade de Brasilia, 70910-900, Brasilia-DF, Brazil aut NATIONALLICENCE 700 1- de A. Siqueira Egle Department of Cellular Biology, Universidade de Brasilia, 70910-900, Brasilia-DF, Brazil aut NATIONALLICENCE 700 1- de Freitas Sonia Department of Cellular Biology, Universidade de Brasilia, 70910-900, Brasilia-DF, Brazil aut NATIONALLICENCE 773 0- Journal of Protein Chemistry Kluwer Academic Publishers-Plenum Publishers 19/6(2000-08-01), 507-513 0277-8033 19:6<507 2000 19 10930 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer