Fac-simile Scheda Linee di Ricerca - Federalimentare

Per quanto riguarda la PPO, sono stati ottenuti interessanti risultati: i) la messa a punto di unefficiente e specifico processo di estrazione in grado di garantirne l’attività catalitica, ii) laproduzione di un estratto enzimatico liofilizzato, facilmente conservabile e perfettamente stabile neltempo, iii) la dimostrazione che la PPO di uva Moscato bianco e Prosecco ha le medesimecaratteristiche di stabilità chimico-fisica delle PPO di altri vitigni internazionali.Grazie all’analisi elettroforetica è stato possibile risolvere numerosi problemi riguardanti lasolubilità del campione e di conseguenza la sua mobilità in condizioni native. L’utilizzo dellatecnica bidimensionale ha confermato come questo metodo possa essere valido anche nello studiodi enzimi estratti da matrici vegetali.Parole chiave- Esterasi- β-glucosidasi- pectin metilesterasi- polifenol ossidasi- zimogrammiDati pubblicati inerenti il tema di ricerca:1) Zocca F., Lomolino G., Curioni A., Spettoli P., Lante A. (2007) Detection of pectinmethylesteraseactivity in presence of methanol during grape pomace storage”, Food Chemistry,102, , 59-65.Methanol is an unwanted component in the production of spirit beverages. Its presence in grape pomace storeduntil distillation greatly affects the composition of the final product, which requires redistillation, modifying thearomatic characteristics of the distillate. Consequently, reduction of methanol, by controlling its formation duringpomace storage, can increase the quality of grappa. The aim of this work was to monitor pectinmethylesteraseactivity during grape pomace storage, in order to identify its presence related to methanol release. The enzymeactivity was detected during various storage times by spectrophotometric and electrophoretic methods. Resultsshow that yeasts do not contribute to PME production. Moreover, by using paranitrophenyl acetate, a specificsubstrate for esterase, also as PME substrate, we demonstrate the presence of several enzymes hydrolysingester bonds.2) Zocca F., Lomolino G., Spettoli P., Lante A. (2007) Deriphat 2-DE to visualize polyphenoloxidase in Moscato and Prosecco grapes”, Electrophoresis, , 28, 3992-3997.The Deriphat 2-DE was used to visualize polyphenol oxidase (PPO) isoforms of Moscato and Prosecco grape extracts,partially purified and characterized. Catecholase has similar values in the two varieties, whereas Moscatocresolase data are almost 54% higher. In the first dimension, the PPO of both varieties may be detected by SDS-PAGE, but native PAGE (N-PAGE) gave negative results. For this reason, the samples were solubilized in thezwitteronic detergent Deriphat, which was also included in the gel and the cathodic buffer. Deriphat migrated togetherwith the cathodic buffer, maintaining protein solubility and revealing the PPO profiles of Moscato andProsecco extracts in native conditions. The combination of Deriphat-PAGE (D-PAGE) and SDS-PAGE (2-DE)also resulted in improved separation efficiency in resolving PPO and specialized stains in evaluating PPO activities.The control, represented by IEF for the first-dimensional separation, had a lower number of spots, demonstratingthe higher capacity of Deriphat 2-DE to isolate PPO isoforms from grape extracts. The Deriphat 2-DEmethod described here is simple but powerful, and the resulting information will be a useful tool for further proteomicresearch.SISTAL - SOCIETA’ ITALIANA DI SCIENZE E TECNOLOGIE ALIMENTARIDipartimento di Scienze e Tecnologie Agroalimentari, Università degli Studi della TusciaVia San Camillo de Lellis, 01100 ViterboTel.: 0761- 35 74 94/7 , Fax: 0761- 35 74 98, e-mail: mmoresi@unitus.it309