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Three Phase Partitioning (TPP) system as an elegant non-chromatographic and bulk separation method was successfully applied for the extraction and recovery of papain from the latex of Carica papaya. The optimized parameters of TPP allowed achieving a purification fold of 11.45 and activity recovery of 134% with 40% (NH4)2SO4, 1.0:0.75 ratio of crude extract: t-BuOH at pH and temperature of 6.0 and 25 °C, respectively. The recovered papain had a molecular weight of 23.2 kDa and revealed maximum activity at pH 6.0 and temperature of 50 °C. The maximum values of Km and Vmax parameters were 10.83 mg mL−1 and 33.33 U mL−1, respectively. The protease with 4 isoforms was stable at 40–80 °C and a pH range of 6.0–7.5 against numerous metal ions and none of them inactivated the recovered protease. Moreover, 10 mM Ca2+ improved 2-folds the activity and half-life of the protease at temperatures from 30 to 50 °C. The milk-clotting activity tests revealed high stability of latex papain at storage, namely at −20 °C compared to 4 °C and 25 °C for up than 5 weeks. As a meat tenderizing agent, it showed promising role under different treatments by improving the texture of tough meat. The findings indicated that one-step TPP system is a simple, quick, economical and very attractive process for fast recovery of latex papain compared to other proposed protocols.

The present work describes for the first time an elegant non-chromatographic method, the three phase partitioning for the purification and recovery of zingibain, a milk-clotting enzyme, from Zingiber officinale rhizomes. Factors affecting partitioning efficiency such as (NH4)2SO4 saturation, crude extract to t-butanol ratio and pH on zingibain partitioning were investigated. Optimal purification parameters were 50% (NH4)2SO4 saturation with 1.0:1.0 ratio of crude extract:t-butanol at pH 7.0, which gave 14.91 purification fold with 215% recovery of zingibain. The enzyme was found to be exclusively partitioned in the aqueous phase. The enzyme showed a prominent single band on SDS-PAGE. It is a monomeric protein of 33.8 kDa and its isoelectric point is 4.38. The enzyme exhibited maximal proteolytic activity at a temperature of 60 °C and pH 7.0. It was found to be stable at 40-65 °C during 2 h. The enzyme was found to be highly stable against numerous metal ions and its activity was enhanced by Ca(2+), K(+) and Na(+). It was completely inhibited by heavy metal ions such as Cu(2+) and Hg(2+) and partially by Cd(+). Zingibain milk-clotting activity (MCA) was found to be highly stable when stored under freezing (-20 °C) for 30 days compared at 4 °C.

Three phase partitioning or TPP consists of proteins’ precipitation due to simultaneous presence of ammonium sulfate and t-butanol. The technique has been successfully used for the partial purification of ficin (EC 3.4.22.3) from Ficus carica latex. In this study, ficin of Mediterranean F. carica was for the first time partially purified and recovered in a single step using TPP. Optimal purification parameters of the system were 40% ammonium sulfate saturation (w/v) with 1.0:0.75 (v/v) ratio of crude extract: t-butanol at pH 7.0, which gave 6.04 purification fold with 167% recovery of ficin. The enzyme was found to be exclusively partitioned in the interfacial precipitate phase. The Tricine SDS–polyacrylamide gel electrophoresis analysis of the enzyme showed comparatively purification and protein molecular weight of the enzyme was nearly found to be 23.4 kDa. Characterization of enzyme showed that optimal pH of purified enzyme was 6.5 and optimal temperature was 60 °C. The enzyme was found to be stable at 40–70 °C for 1 h. This study showed that TPP is a simple, economical and quick method for ficin recovering from F. carica latex trees and can be performed in a purification process to be used successfully in food industries.