Objective: Three phase partitioning (TPP) is a simple and economical purification and recovery technique for proteins and also enzymes. In this technique; proteins are separated in the interfacial or lower phase while contaminant parts of crude extract partitioning occur in the upper organic phase. In this study invertase was purified and recovered from potato by TPP.
Methods:The highest enzyme recovery of 121% and purification fold 5.67 was seen in the aqueous phase at the 20% ammonium sulfate saturation with 1.0: 1.0 t-butanol ratio at the first cycle of partitioning. The TPP was optimized by adding ammonium sulfate to final concentration at 25% with the constant t-butanol ratio to starting material. Results: Purification fold and activity recovery were found as 12.8 and 156%, respectively. The Km value, optimal temperature and optimal pH of purified enzyme were also determined.
Conclusion:The present study showed that, TPP can be an attractive and effective technique for the extraction of invertase from potato. Key Words: TPP, invertase, recovery, purification, potato tuber.
Conflict of Interest:The authors declare no conflict of interest.
ÖZETAmaç: Üçlü faz ayrılması proteinleri ve enzimlerin geri kazanılması ve saflaştırılması için ekonomik ve basit bir yöntemdir. Bu yöntemde proteinler sulu ya da ara fazda toplanırken; ham enzimin kontamine içeriği üst kısımdaki organik fazda toplanma eğilimindedir. Bu çalışmada patates yumrularında üçlü faz ayrılması ile invertaz saflaştırılması ve geri kazanımı gerçekleş-tirilmiştir. Metod: Üçlü faz ayrımı iki döngüde gerçekleştirilmiştir. birinci döngüde enzim %121 geri kazanım ve 5.67 saflaştırma katsayısı ile %20 amonyum sülfat doygunluğunda ve1 ). The reaction was incubated at 37 ºC for 30 min then was stopped by adding 0.1 ml of DNS (3,5-Dinitrosalicylic acid) reagent. The mixture was heated in a boiling water bath for 5 min. It was then cooled in ice bath and the amount of reducing sugars was measured spectrophotometrically at 540 nm [22]. The data presented for all invertase activity determinations are mean values of duplicate assay. One unit of invertase activity was defined as the amount of enzyme which released 1 µmole of glucose from sucrose per minute at pH 4.7 and 37 ºC.
Protein concentrationConcentration of the protein was determined by Bradford method [23] using Coomassie brilliant blue G-250 dye as a reagent and bovine serum albumin (BSA) as standard, by measuring the absorbance at 595nm at 25 ºC. Assays were performed in duplicate and the averages were used in calculations.
Three-phase partitioning
Effect of t-butanolTPP experiments were carried out by employing various t-butanol ratios (crude extract:t-butanol; 1.0:0.5, 1.0:1.0, 1.0:1.5, 1.0:2.0) with a constant ammonium sulfate saturation at 20% (w/v). The mixture was mixed gently and then allowed to stand for 30 min at 37 ºC. Afterwards the mixture was centrifuged at 5000 rpm for 10 min at +4 ºC to facilitate the separation of phases. The lower aqueous phase and the interfacial phase were coll...