caa a22 4500 378849646 CHVBK 20180305123320.0 cr unu---uuuuu 161128e20030127xx s 000 0 eng 10.1515/BC.2003.010 doi (NATIONALLICENCE)gruyter-10.1515/BC.2003.010 Nuclear Magnetic Resonance Studies on thepKa Values and Interaction of Ionizable Groups in Bromelain Inhibitor VI from Pineapple Stem [Elektronische Daten] [K.-i. Hatano, M. Kojima, M. Tanokura, K. Takahashi] Bromelain inhibitor VI (BI-VI), a cysteine proteinase inhibitor from pineapple stem, is a unique doublechain molecule composed of two distinct domains A and B. In order to clarify the molecular mechanism of the proteinase-inhibitor interaction, we investigated the electrostatic properties of this inhibitor. The inhibitory activity toward bromelain was revealed to be maximal at pH 3-4 and the gross conformation to be stable over a wide range of pH. Based on these results, pH titration experiments were performed on the proton resonances of BI-VI in the pH range of 1.5-9.9, and p values (pKaKexp) were determined for all carboxyl groups and α-amino groups. The pKexp were also compared with theoretical values calculated from the NMR-derived structures of BI-VI. The electrostatic surface potential map constructed using the pKexp values revealed that BI-VI possesses continuous negatively charged and scattered positively charged regions on the molecular surface and both regions appear to serve for docking properly with a basic target enzyme. Furthermore, it was suggested that the ionic interaction of the inhibitor with the target enzyme is primarily important for the inhibition, which seems to involve some carboxyl groups in the inhibitor and a thiol group in the proteinase. Copyright © 2003 by Walter de Gruyter GmbH & Co. KG Biochemistry nationallicence Molecular biology nationallicence Cellular biology nationallicence Hatano K.-i aut Kojima M. aut Tanokura M. aut Takahashi K. aut Biological Chemistry Walter de Gruyter 384/1(2003-01-27), 93-104 1431-6730 384:1<93 2003 384 bchm https://doi.org/10.1515/BC.2003.010 text/html Onlinezugriff via DOI 1 research article jats NATIONALLICENCE 856 40 https://doi.org/10.1515/BC.2003.010 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Hatano K.-i aut NATIONALLICENCE 700 1- Kojima M. aut NATIONALLICENCE 700 1- Tanokura M. aut NATIONALLICENCE 700 1- Takahashi K. aut NATIONALLICENCE 773 0- Biological Chemistry Walter de Gruyter 384/1(2003-01-27), 93-104 1431-6730 384:1<93 2003 384 bchm CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-gruyter