Enzymatic hydrolysis of penicillin G to 6-aminopenicillanic acid in cloud point system with discrete countercurrent experiment

Improved X-ray diffraction from Bacillus megaterium penicillin G acylase crystals through long cryosoaking dehydration

Penicillin G acylase from Bacillus megaterium (BmPGA) is currently used in the pharmaceutical industry as an alternative to PGA from Escherichia coli (EcPGA) for the hydrolysis of penicillin G to produce 6-aminopenicillanic acid (6-APA), a penam nucleus for semisynthetic penicillins. Despite the significant differences in amino-acid sequence between PGAs from Gram-positive and Gram-negative bacteria, a representative PGA structure of Gram-positive origin has never been reported. In this study, crystallization and diffraction studies of BmPGA are described. Poor diffraction patterns with blurred spots at higher resolution were typical for BmPGA crystals cryocooled after a brief immersion in cryoprotectant solution. Overnight soaking in the same cryo-solution substantially improved both the mosaicity and resolution limit through the establishment of a new crystal-packing equilibrium. A crystal of BmPGA diffracted X-rays to 2.20 Å resolution and belonged to the monoclinic space group P2(1) with one molecule of BmPGA in the asymmetric unit.

Immobilization of penicillin G acylase on macro-mesoporous silica spheres

In this study, macro-mesoporous silica spheres were prepared with a micro-device and used as the support for the immobilization of penicillin G acylase (PGA). To measure the enzymatic activity, the silica spheres with immobilized PGA were placed into a packed-bed reactor, in which the hydrolysis of penicillin G was carried out. The influences of the residence time, the initial concentration of the substrate, the accumulation of the target product 6-aminopenicillanic acid, and the enzyme loading amount on the performance of the immobilized PGA were investigated. The introduction of macropores increased the enzyme loading amount and decreased the internal mass transfer resistance, and the results showed that the enzyme loading amount reached 895 mg/g (dry support), and the apparent enzymatic activity achieved up to 1033 U/g (dry support). In addition, the immobilized PGA was found to have great stability.

The potential of cloud point system as a novel two-phase partitioning system for biotransformation

Although the extractive biotransformation in two-phase partitioning systems have been studied extensively, such as the water-organic solvent two-phase system, the aqueous two-phase system, the reverse micelle system, and the room temperature ionic liquid, etc., this has not yet resulted in a widespread industrial application. Based on the discussion of the main obstacles, an exploitation of a cloud point system, which has already been applied in a separation field known as a cloud point extraction, as a novel two-phase partitioning system for biotransformation, is reviewed by analysis of some topical examples. At the end of the review, the process control and downstream processing in the application of the novel two-phase partitioning system for biotransformation are also briefly discussed.