Sainan Su

Optimization of adsorption conditions of papain on dye affinity membrane using response surface methodology.

The adsorption of papain on Reactive Blue 4 dye-ligand affinity membrane was investigated in a batch system. The combined effects of operating parameters such as initial pH, temperature, and initial papain concentration on the adsorption were analyzed using response surface methodology. The optimum adsorption conditions were determined as initial pH 7.05, temperature 39 degrees C, and initial papain concentration 11.0mg/ml. At optimum conditions, the adsorption capacity of dye-ligand affinity membrane for papain was found to be 27.85 mg/g after 120 min adsorption. The papain was purified 34.6-fold in a single step determined by fast protein liquid chromatography. More than 85% of the adsorbed papain was desorbed using 1.0M NaCl at pH 9.0 as the elution agent. The purification process showed that the dye-ligand immobilized composite membrane gave good separation of papain from aqueous solution.

Comparison: Adsorption of papain using immobilized dye ligands on affinity membranes

Novel membranes that involve the immobilization of Reactive Red 120 or Reactive Brown 10 as dye ligands were prepared. These were used in the purification of papain from papaya powder extracts. Papain adsorption capacities for the Red 120 and Brown 10 membranes were 143.6 mg/g and 107.3mg/g, respectively. The effectiveness of adsorption was demonstrated by Freundlich isotherm proficiency. The enzyme was eluted from the respective dye membranes using 1.0M NaCl at pH 6.0 and yields of over 80% were found for the Red 120-CS (chitosan)-nylon membrane whereas only a 50% recovery was possible using the Brown 10-CS-nylon membranes. It is concluded that Red 120-CS-nylon membranes could play an active role in the separation and purification of papain from crude extracts. This system has the potential to be developed for the commercial isolation of the protein.

Improving the Stability of Cellulase by Immobilization on Chitosan-Coated Magnetic Nanoparticles Modified alpha-Ketoglutaric Acid

The application of cellulases in various industries demands highly stable enzymes, able to perform at extreme pH values and temperatures. In this study, the cellulase, which was immobilized on the chitosan-coated magnetic nanoparticles modified with alpha-ketoglutaric acid (alpha-KA-CCMNPs), exhibited a broader pH range of high activity and the loss of the activity of immobilized cellulase was lower than that of free cellulase. And the optimal temperature for immobilized cellulase was 50degC, whereas that for free cellulase was 40degC. Meanwhile, the immobilized cellulase showed better thermal stability than free cellulase at high temperature range. In addition, the storage stability of the cellulase was improved greatly after it was immobilized on the surface of alpha-KA-CCMNPs.

Isotherm, Kinetic and Thermodynamic Analysis of Bromelain Adsorption on Reactive Blue 4 Immobilized Composite Membranes

The behavior of bromelain adsorption on the dyeligand affinity membrane was investigated at 277,298 and 310K, which was chitosan (CS) coated to decrease the non-specific adsorption of protein. Reactive Blue 4 was immobilized onto the CS-coated nylon membrane as an affinity ligand. In order to examine the rate limiting step of Reactive Blue 4-immobilized composite membrane adsorption, the two adsorption kinetic model: the pseudo-first-order and the pseudo-second-order were tested with the experiment data. Results indicated that Freundlich isotherm was able to adequately describe the adsorption of bromelain on dye affinity membranes. It was also found that the pseudo-first-order kinetic model described the bromelain adsorption process with a good fitting. Keywords-adsorption; bromelain; Reactive Blue 4; isotherm; kinetic; thermodynamic

Papain Immobilization on Chitosan-Coated Nylon Membrane: Preparation and Its Application in Cystatin Separation

Nylon membranes are first hydrolyed with dilute HCl and then treated with chitosan before being used as the affinity carrier. Papain as a ligand has been immobilized on the activated membranes with glutaraldehyde as a crosslinking agent. The factors involving with the activity of immobilized papain, such as concentration of glutaraldehyde, pH, temperature, reaction time, and the amount of added papain have been studied. The results show that the optimum conditions for the preparation of immobilized papain nylon affinity membranes are as follows: pH 9.0, 0.5% glutaraldehyde solution, the concentration of added papain is 10 mg/ml, the reaction time is 6 h at 45degC. The nylon membrane prepared is then used to purify cystatin from potato juice, and shows that they are high efficiency affinity membranes base for cystatin separation.