Search results

Using a reversible addition fragmentation chain transfer reaction, a series of resins were prepared by using N, N-diethyl acrylamide (DEA), poly (ß-hydroxyethyl methacrylate) (PHEMA) as hydrophilic blocks and poly (glycidyl methacrylate) (PGMA) as hydrophobic blocks (and as a target for immobilizing penicillin G acylase [PGA]) and the low critical solution temperature (LCST) of which could be adjusted by changing the segment length of blocks.

To make the catalytic conversion temperature of immobilized PGA fallen into the temperature range of the sol state of thermosensitive block resin, a type of thermosensitive block resin, i.e. PDEA-b-PHEMA-b-PGMA (DHGs) was synthesized to immobilize PGA, and the effect of segment order of block resin was investigated on the performance of PGA.

Carrier prepared with monomers molar ratio of n(DEA) : n(HEMA): n(GMA) = 100: 49: 36 presented loading capacity (L) and enzyme activity recovery ratio (Ar) of 110 mg/g and 90%, respectively, and a block resin with LCST value of 33 °C was essential for keeping higher Ar of PGA.

PGA has become an important biocatalyst in modern chemistry industry. However, disadvantages include difficulty in separation, poor repeatability and high cost, which limits the scope of PGA applications. The effective method is to immobilize the enzyme to the carrier, which could overcome the disadvantage of free enzyme.

To save the economic cost and improve the performance of enterprises, this study aims to synthesize high performance immobilized penicillin G acylase (PGA) carriers with fast reaction speed, high recovery rate of enzyme activity and good reusability through corresponding theoretical guidance and experimental exploration.

A diblock resin was synthesized by reversible addition-fragmentation chain transfer polymerization method using N, N-diethylacrylamide (DEA) and β-hydroxyethyl methacrylate (HEMA) as functional monomers poly(N, N-diethylacrylamide)-b-poly(β-hydroxyethyl methacrylate) (PDEA-b-PHEMA) was obtained, and the effect of the ratio of DEA and HEMA on the activity of PGA was investigated, and the appropriate block ratio of DEA and HEMA was obtained. After that, the competitive rate of HEMA and glycidyl methacrylate (GMA) under the carrier preparation conditions was investigated. Based on the above work, a thermosensitive resin carrier PDEA-b-PHEMA-b-P(HEMA-co-GMA) with different target distances was synthesized, and the chemical structures and molecular weight of copolymers were investigated by hydrogen NMR (¹H NMR).

The lower critical solution temperature of the resin support decreases with the increase of the monomer HEMA in the random copolymerization; the catalytic performance study indicated that the response rate of the immobilized PGA is fast, and the recovery rate of the enzyme activity of the immobilized PGA varies with the distance between the targets. When the molar ratio of HEMA to GMA in the resin block is 8.15:1 [i.e. resin PDEA100-b-PHEMA10-b-P(HEMA65-co-GMA8)], the activity recovery rate of immobilized PGA can reach 50.51%, which was 15.49% higher than that of pure GMA immobilized PGA.

This contribution provides a novel carrier for immobilizing PGA. Under the optimal molar ratio, the enzyme activity recovery could be up to 50.51%, which was 15.49% higher than that of PGA immobilized on the carrier with nonregulated distance between two immobilization sites.