Purification of phenylalanine ammonia-lyase in PEG1000/Na2SO4 aqueous two-phase system by a two-step extraction

Bioconjugation of enzyme with silica microparticles: a promising platform for α-amylase partitioning

Here, we report the implementation of α-amylase conjugated silica microparticles for improvement of α-amylase partitioning in a PEG-organic salt-based aqueous two phase system. A direct reduction method was employed for the synthesis of silica microparticles with simultaneous introduction of α-amylase. In this context, we synthesized three different silica α-amylase conjugated microparticles with variation of tetraethyl orthosilicate concentration, and thus the effect of final particle size and enzyme loading on partitioning was also studied. The partition coefficient ratio of α-amylase to Si:α-amylase of 2.186 : 21.701 validated an almost tenfold increase in separation. The microscopic structure of the system was thoroughly investigated in order to understand the extraction mechanism and any possible denaturation. Improved partition coefficients can be interpreted by the formation of α-amylase-silica-PEG carriers. Furthermore, circular dichroism (CD) spectra validated partial unfolding of the enzyme.

Influence of process variables on extraction of Cefalexin in a novel biocompatible ionic liquid based-aqueous two phase system

Despite the fact that ionic liquid-based aqueous two phase systems (ATPSs) have been widely studied for extraction purposes, the adequacy of biodegradable organic salts as salting out agents has been left unexploited.

Biotechnological production and applications of microbial phenylalanine ammonia lyase: a recent review

Phenylalanine ammonia lyase (PAL) catalyzes the nonoxidative deamination of l-phenylalanine to form trans-cinnamic acid and a free ammonium ion. It plays a major role in the catabolism of l-phenylalanine. The presence of PAL has been reported in diverse plants, some fungi, Streptomyces and few Cyanobacteria. In the past two decades, PAL has gained considerable significance in several clinical, industrial and biotechnological applications. Since its discovery, much knowledge has been gathered with reference to the enzyme's importance in phenyl propanoid pathway of plants. In contrast, there is little knowledge about microbial PAL. Furthermore, the commercial source of the enzyme has been mainly obtained from the fungi. This study focuses on the recent advances on the physiological role of microbial PAL and the improvements of PAL biotechnological production both from our laboratory and many others as well as the latest advances on the new applications of microbial PAL.

Purification of alkaline protease from chicken intestine by aqueous two phase system of polyethylene glycol and sodium citrate

An aqueous two phase system of polyethylene glycol (PEG) and salts was evaluated for separation and purification of alkaline proteases from chicken intestine. Among the different salts evaluated potassium phosphate and sodium citrate gave higher enzyme yield (73.5% and 69.7% respectively) and enzyme purification (5.3 and 7.4 fold) in PEG rich upper phase. Increase in concentration of sodium citrate in the system resulted in reduction in enzyme yield and enzyme purification factor, with 15% salt showing highest enzyme yield (59.8%) and purification (6.7 fold). Initial protein concentration in the system did not show any specific trend on the partition behavior of the enzyme. The temperature at which the system is incubated did not show any significant (p ≥ 0.05) effect on enzyme partition and purification. Increasing the PEG concentration in the system from 15 to 25% resulted in reduction in enzyme yield from 53.7 to 21.9% and enzyme purification from 5 fold to 1.4 fold in PEG rich upper phase. pH also had a significant (p < 0.05) effect on the partition of the enzyme to the upper phase with highest purification (3.4 fold) at pH 9.0 and higher enzyme yield (46.2%) at pH 10.

Modeling and optimization of phenylalanine ammonia lyase stabilization in recombinant Escherichia coli for the continuous synthesis of l-phenylalanine on the statistical-based experimental designs

Some approaches for improving recombinant phenylalanine ammonia lyase (PAL) stability in Escherichia coli during the enzymatic methods of l-phenylalanine (l-Phe) production were developed following preliminary studies by means of statistical-based experiment designs (response surface method). The traditional non-statistical technology was used to screen four critical factors for PAL stability during the bioconversion process, viz., glycerin, sucrose, 1,4-dithiothreitol (DTT), and MgSO(4). The central composite design (CCD) was applied to optimize the combined effect of critical factors for recombinant PAL stability and understand the relationship between the factors and PAL stability. The optimum values for testing variables were 13.04 mM glycerin, 1.87 mM sucrose, 4.09 mM DTT, and 69 mM Mg(2+). A second-order model equation was suggested and then validated experimentally. The model adequacy was very satisfactory because the coefficient of determination was 0.88. The maximum PAL activity was retained as 67.73 units/g after three successive cycles of bioconversion. In comparison to initial PAL activity, the loss of PAL activity was only 22%. PAL activity was enhanced about 23% in comparison to the control (without any stabilizer additives). PAL stability was significantly improved during successive bioconversion. The results obtained here verified the effectiveness of the applied methodology and may be helpful for l-Phe production on an industrial scale.