RT info:eu-repo/semantics/article T1 Structural changes of a protein extract from apple with polyphenoloxidase activity obtained by cationic reversed micellar extraction induced by high-pressure carbon dioxide and thermosonication A1 Illera Gigante, Alba Ester A1 Beltrán Calvo, Sagrario A1 Sanz Díez, Mª Teresa K1 Ingeniería química K1 Chemical engineering AB Polyphenoloxidase from apple was extracted and further concentrated by cationic reversed micellar extraction. Previous to reversed micellar extraction a crude protein extract was obtained using AG2-X8 as adsorbent of phenolic compounds and the detergent Triton X-100. Forward and backward extraction conditions were optimized by using dodecyl trimethyl ammonium bromide as surfactant in the organic phase. Optimization was carried out to obtain the highest value of PPO activity recovery and the purification fold at the different experimental conditions. Under the optimum extraction conditions, PPO activity recovery was 99% and purification fold reached a value of 17, showing that reversed micellar extraction was a good technique as a first step to concentrate on a targeted enzyme. After removing some impurities by centrifuge ultrafiltration, the protein extract with PPO activity was treated by pressurized carbon dioxide and thermosonication achieving residual PPO activity values of 16 ± 3 and 9 ± 1%, respectively. Quenching experiments by iodide performed in the non-treated extract and in the treated extracts revealed conformational changes of this protein fraction reflected in the greater exposure of the fluorophore to the quencher. PB Nature Research YR 2019 FD 2019-09 LK http://hdl.handle.net/10259/5160 UL http://hdl.handle.net/10259/5160 LA eng NO Spanish Government (MINECO) and the European Regional Development Fund (ERDF) for financialsupport of project CTQ2015-64396-R and AEI’s contract, and to Junta de Castilla y León and ERDF for financialsupport of project BU301P18. DS Repositorio Institucional de la Universidad de Burgos RD 28-mar-2024