Free Penicillin G Acylase Research Articles

Synthesis of polymer-functionalized β-cyclodextrin, Mg2+ doped, coating magnetic Fe3O4 nanoparticle carriers for penicillin G acylase immobilization

Based on the beneficial effects of magnesium ions on biomolecules, it was first introduced into enzyme immobilization carriers to promote the comprehensive performance of immobilized enzymes in repeated use. Firstly, Fe3O4 nanoparticles (NPs) were prepared by the inverse microemulsion method, then, Mg2+ was doped in the process of coating β-cyclodextrin (β-CD) on the surface of Fe3O4 NPs. Afterward, through acetal reaction, glutaraldehyde (GA) was grafted to the material’s surface to obtain Mg2+-Fe3O4 @ β-CD-g-GA NPs, and covalent bond immobilization of Penicillin G acylase (PGA) was realized by the Schiff base reaction of the carriers’ aldehyde group and PGA’s amino group. After optimization of process conditions, the results show that the performances of the immobilized PGA achieve the best, when the concentration of the enzyme solution is 3.00 vol%, pH is 8.0, the immobilization time is 30 h, and the immobilization temperature is 37 °C. Its enzyme activity recovery (EAR), enzyme activity (EA) and enzyme loading capacity (ELC) are 95.6%, 31997 U/g, 110 mg/g, respectively. Lastly, the operational stability, reusability, and storage stability of Mg2+-Fe3O4 @ β-CD-g-GA-PGA NPs were researched. Relative to free PGA, immobilized PGA has better operation stability and storage stability. After 11 repeated uses, the immobilized PGA still has 56% of the initial vitality, and the carrier recovery (Re) is 86.6%.

Immobilization and Evaluation of Penicillin G Acylase on Hydroxy and Aldehyde Functionalized Magnetic α-Fe2O3/Fe3O4 Heterostructure Nanosheets.

Magnetic α-Fe2O3/Fe3O4 heterostructure nanosheets were fabricated via hydrothermal calcination. The activity of penicillin G acylase (PGA), which was covalently immobilized onto silica-decorated heterostructure nanosheets, achieved the highest activity of 387.03 IU/g after 18 h of incubation with 0.1 ml of PGA. In contrast, the activity of free PGA reached the highest level when the temperature was 45°C with a pH of 8.0. However, the activity of free PGA changed more dramatically than immobilized PGA as the relative conditions changed. Moreover, the Michaelis–Menten constant (Km) and reusability of immobilized PGA were also explored. The results showed that free PGA Km and maximum rate (Vmax) were 0.0274 M and 1.167 μl/min, respectively. Km and Vmax values of immobilized PGA were 0.1082 M and 1.294 μl/min, respectively. After 12 cycles of repetitive use, immobilized PGA remained approximately 66% of its initial activity, indicating that the PGA immobilized onto the heterostructure nanosheets showed better stability and reusability than free PGA.

Sandwich-likely structured, magnetically-driven recovery, biomimetic composite penicillin G acylase-based biocatalyst with excellent operation stability

Immobilization of penicillin G acylase (PGA) on carrier was an established approach to improve the stability and reusable property of it. Herein, Magnetic Fe3O4 nanoparticles (Fe3O4 NPs) that coated by poly (tannic acid), named as Fe3O4 @PTA nanoparticles (Fe3O4 @PTA NPs), had been used as carrier for immobilizing of PGA by physical adsorption effect to produce Fe3O4 @PTA-PGA NPs. Then Fe3O4 @PTA-PGA NPs was post-modified by spontaneous in-situ self-polymerization of dopamine to prepare polydopamine (PDA) coated Fe3O4 @PTA-PGA/PDA nanocapsule. Fe3O4 @PTA-PGA/PDA nanocapsule with sandwich-like structure was a biomimetic composite penicillin G acylase-based biocatalyst, having excellent operational stability. The response rate of Fe3O4 @PTA-PGA/PDA nanocapsule decreased with the extension of polymerization time, whereas the storage stability, thermal stability and pH stability increased with the extension of polymerization time. The EAR of Fe3O4 @PTA-PGA/PDA nanocapsule was 76.4 % with PDA coating time of 4 h. The relative activity (Rt) of Fe3O4 @PTA-PGA/PDA magnetic nanocapsule was 87.1 %, while that of free PGA was 12.5 % after 90 days of storage. Moreover, the Fe3O4 @PTA-PGA/PDA nanocapsule still had 94.1 % of its initial enzyme activity retained and with a enzyme recovery ratio (Re) of 98.0 % after 12 cycles of repeated usage. All those results indicated that the Fe3O4 @PTA-PGA/PDA nanocapsule had excellent operation stability and reusable property, which was very promising for being used as biocatalyst in industrial applications.

Preparation of Magnetic Temperature-Sensitive Polymer Composite Carrier and Study on Immobilized Penicillin G Acylase

This work designed and prepared a novel type of carrier for immobilization of penicillin G acylase (PGA), and then the performances of the immobilized PGA were studied in detail. The process is presented as follows: First, dopamine (DA), an adhesive biological secondary metabolite, was adopted to form a polydopamine (PDA) coating on the surface of Fe3O4nanoparticles (NPs) prepared by the inverse microemulsion method to generate Fe3O4@PDA NPs through in-situ polymerization. After that, the obtained Fe3O4@PDA NPs were modified by reversible addition fragmentation chain transfer (RAFT) reagent containing carboxyl groups on its surface. Then, taking N,N diethyl acrylamide (DEA) as the temperature-sensitive monomer, [Formula: see text]-hydroxyethyl methacrylate (HEMA) as the hydrophilic monomer, glycidyl methacrylate (GMA) as the target monomer and methyl methacrylate (MMA) as the monomer controlling the distance between targets, through the “Grafting from” strategy and the RAFT polymerization method, the magnetic temperature-sensitive polymer composite, Fe3O4@PDA-g-PDEA-b-PHEMA-b-P(MMA-co-GMA) NPs with different feeding ratios of MMA/GMA, was prepared to realize the immobilization of penicillin G acylase (PGA). Based on samples prepared at each stage of the carrier, the structure and performances were characterized by Fourier Infrared Spectroscopy (FTIR), Transmission Electron Microscope (TEM), X-ray Diffraction (XRD), and Vibration Specimen Magnetometer (VSM), respectively. Besides, the content of RAFT graft Fe3O4@PDA was also quantitatively characterized by ICP, and the molecular weight of the polymer was characterized by mass spectrometry. Result showed that the target space influenced enzyme load capacity (ELC), enzyme activity (EA) and enzyme activity recovery rate (EAR) at a large degree, and there was no positive relationship between ELC to EA and EAR. Last, performances of the immobilized PGA, including relative enzyme activity ([Formula: see text]) of immobilized PGA, were 83.9% after storing for 90 days, and 90.3% of the initial activities were still retained after 12 times of repeated use, and the catalytic stability (temperature, pH) and Michaelis–Menten const [Formula: see text] were investigated with free PGA as control if operation was allowed.

Immobilized penicillin G acylase with enhanced activity and stability using glutaraldehyde-modified polydopamine-coated Fe3 O4 nanoparticles.

In this work, Fe3 O4 nanoparticles (NPs) were coated with polydopamine (PDA) to structure Fe3 O4 @PDA NPs by the spontaneous oxygen-mediated self-polymerization of dopamine (DA) in an aqueous solution of pH=8.5. The fabricated Fe3 O4 @PDA NPs were grafted by glutaraldehyde to realize the immobilization of penicillin G acylase (PGA) under mild conditions. The carriers of each stage were characterized and investigated by transmission electron microscopy, X-ray diffraction, Fourier transform infrared, and vibrating sample magnetometry. To improve the catalytic activity and stability of immobilized PGA, the immobilization conditions were investigated and optimized. Under the optimal immobilization conditions, the enzyme loading capacity, enzyme activity, and enzyme activity recovery of immobilized PGA were 114mg/g, 26,308U/g, and 78.5%, respectively. In addition, the immobilized PGA presented better temperature and pH stability compared with free PGA. The reusability study ensured that the immobilized PGA showed an excellent repeating application performance. In particular, the recovery rate of immobilized PGA could reach 94.8% and immobilized PGA could retain 73.0% of its original activity after 12 cycles, indicating that the immobilized PGA exhibited a high operation stability and broad application potential in the biocatalysis field.

The immobilization of penicillin G acylase on modified TiO2 with various micro-environments

Immobilization of penicillin G acylase (PGA) on carriers is an effective strategy for running away from the drawbacks of free PGA. In this work, modified TiO2 was employed as a carrier for the immobilization of PGA. Firstly, TiO2 was used as a nucleus and modified by two different approaches, one-step modification and two-step modification, to construct and regulate the micro-environment of carrier, particularly by changing the type of functional immobilization groups, and the arm-length of immobilization sites. In the one-step modification approach, TiO2 was altered by glutaraldehyde, 3-glycidoxypropyltrimethoxysilane (3-GCDPTMS) and 3-aminopropyltriethoxysilane (3-APTMS), separately; while in the two-step modification approach, primary TiO2 was firstly altered with a small amount of glutaraldehyde or 3-GCDPTMS, then followed by a secondary modification process using glutaraldehyde and 3-GCDPTMS, respectively. Secondly, the influence of the micro-environments of carrier on the catalytic performance of immobilized PGA, in terms of enzyme loading capacity (ELC), enzyme activity (EA) and activity retention ratio (EAR) was investigated. Results revealed that PGA immobilized on carrier modified by 3-GCDPTMS, with a graft rate of 30 % had the best performance, which had an ELC of 10,800 U, EA of 14,900 U/g. Both of the functional group and arm-length of immobilization site had influence on the catalytic performance of immobilized PGA, and the functional groups of immobilization site was the most essential one responsible for stabilizing PGA and improving its catalytic activity. Then PGA immobilized carrier with longer arm-length had better catalytic performance.

Efficient synthesis of cefadroxil in [Bmim][NTf2]‐phosphate cosolvent by magnetic immobilized penicillin G acylase

AbstractFor the first time, cefadroxil was synthesized from 7‐Amino‐3‐desacetoxycephalosporanic acid and d‐hydroxyphenylglycine methyl ester in [Bmim][NTf2]‐phosphate cosolvent capable of dissolving the substrates using the penicillin G acylase (PGA) immobilized on the micrometer‐size magnetic polymer microspheres having high activity of 2,083 U/g. The high synthesis/hydrolysis (S/H) ratio of 1.12 was achieved with 79.0% yield, where only the S/H ratio of 0.19 and yield of 20.0% was obtained using free PGA under the identical optimum reaction conditions. Cefadroxil had been synthesized efficiently in [Bmim][NTf2]‐phosphate cosolvent by the magnetic immobilized PGA, which illuminated that there are two very critical and essential designs, that is, effective support and suitable solvent system by PGA, in enzymatic synthesis of cefadroxil. Obviously, there is great potential for the magnetic immobilized PGA and ionic liquid solvent in application to biocatalysis.

Poly-lysine supported cross-linked enzyme aggregates of penicillin G acylase and its application in synthesis of β-lactam antibiotics

Penicillin G acylase (PGA) from Providencia rettgeri PX04 (PrPGA) was utilized to synthesize β-lactam antibiotics. Poly-lysine supported cross-linked enzyme aggregates (PL-CLEAs) were prepared using PGA. Addition of poly-lysine significantly increased retention of PGA activity in CLEAs, with a decrease in the synthesis/hydrolysis (S/H) ratio. PL-CLEAs with 0.56 mg/mL poly-lysine retained 83% of free PGA activity, and displayed a higher S/H ratio than that of the free enzyme. Both PL-CLEAs and CLEAs exhibited high pH and thermal stabilities. PL-CLEAs possessed the best stability profile, and the lowest α value [(kcat/Km)Ps/(kcat/Km)AD], and was most effective at amoxicillin synthesis. A >94% yield of amoxicillin was achieved using a D-HPGME/6-APA ratio of 1.2:1 (240 mM, 200 mM), with fed-batch addition of D-HPGME. PL-CLEAs displayed excellent operational stability during amoxicillin synthesis. Over 97% of initial conversion was retained after twenty rounds of catalysis. PL-CLEAs exhibited greater potency than CLEAs in practical catalysis, permitting a higher concentration of reactants.

Immobilization and Performance of Penicillin G Acylase on Magnetic Ni0.7Co0.3Fe2O4@SiO2-CHO Nanocomposites.

Magnetic Ni0.7Co0.3Fe2O4 nanoparticles that were prepared via the rapid combustion process were functionalized and modified to obtain magnetic Ni0.7Co0.3Fe2O4@SiO2-CHO nanocomposites, on which penicillin G acylase (PGA) was covalently immobilized. Selections of immobilization concentration and time of fixation were explored. Catalytic performance of immobilized PGA was characterized. The free PGA had greatest activity at pH 8.0 and 45oC while immobilized PGA's a ctivities peaked a t pH 7.5 and 45°C. Immobilized PGA had better thermal stability than free PGA at the range of 30-50°C for different time intervals. The activity of free PGA would be 0 and that of immobilized PGA still retained some activities at 60°C after 2 h. Vmax and Km of immobilized PGA were 1.55 mol/min and 0.15 mol/l, respectively. Free PGA's Vmax and Km separately were 0.74 mol/min and 0.028 mol/l. Immobilized PGA displayed more than 50% activity after 10 successive cycles. We concluded that immobilized PGA with magnetic Ni0.7Co0.3Fe2O4@SiO2-CHO nanocomposites could become a novel example for the immobilization of other amidohydrolases.

Covalent immobilization and characterization of penicillin G acylase on amino and GO functionalized magnetic Ni0.5Zn0.5Fe2O4@SiO2 nanocomposite prepared via a novel rapid-combustion process

Magnetic Ni0.5Zn0.5Fe2O4@SiO2 nanocomposite was prepared via the rapid combustion process, and its surface was modified to obtain amino-functionalized magnetic Ni0.5Zn0.5Fe2O4@SiO2-NH2 nanocomposite. The modified nanocomposite was loaded on graphene oxide (GO), on which penicillin G acylase (PGA) was covalently immobilized. The structure for docking was visualized between PGA and penicillin G using the PyMol program, which revealed the configuration of the active site. Selections of immobilization conditions including immobilization concentration and time of fixation, were explored. The catalytic performance of the immobilized PGA was characterized. The immobilized and free PGA had the highest activity at pH 8.0 and 45 °C. Compared with the activity of the free PGA, the activity of the immobilized PGA was affected less by pH and temperature. The immobilized PGA exhibited the high-effective activity and good stability. Vmax and Km of immobilized PGA were 0.8123 mol·min−1 and 0.0399 mol·L−1, respectively. Free PGA's Vmax and Km were 0.6854 mol·min−1 and 0.0328 mol·L−1. Immobilized PGA remained >70% in relative activity after 9 successive cycles.

The engineering and immobilization of penicillin G acylase onto thermo‐sensitive tri‐block copolymer system

In this work, the relationships between catalytic performances of penicillin G acylase (PGA) and the molar ratio of carrier, thermo‐sensitive tri‐block polymer, poly (N,N‐diethylacrylamide‐b‐ β‐hydroxyethyl methacrylate‐b‐glycidyl methacrylate) (PDEA‐b‐PHEMA‐b‐PGMA) were studied firstly, and result documented the optimal molar ratio was nDEA:nHEMA:nGMA = 100:47:24, which presented a suitable lower critical solution temperature (LCST) of 35°C and the activity retention ratio of 80.62% (±0.50%). Based on the suitable carrier, immobilization conditions were investigated and optimized. When pH of solution, concentration of PGA, immobilized time, and immobilization temperature were 8.0, 1/10 (m/v), 16 hours, and 36°C, respectively, enzyme loading capacity (L), enzyme activity (Ea), and activity retention ratio (Ar) of PGA arrived at the highest value of 21 223 U, 16 199 U/g, and 93.50% (±0.50%), respectively. Besides, the response rate (Rr) of immobilized PGA was the same as free PGA, the reusable stability (Rs) was 77.00% (±1.00%) after using for 11 times, which indicated that the carrier has better compatibility with L, Ar, Rs, and Rr.

Enzyme@silica hybrid nanoflowers shielding in polydopamine layer for the improvement of enzyme stability

In this study, a novel kind of flower-like monodisperse silica nanoparticles (silica nanoflowers) were successfully synthesized based on the microemulsion phase composed of water-surfactant-oil ternary systems. The obtained silica nanoflowers were used to immobilize penicillin G acylase (PGA). The maximum adsorption capacity of immobilized PGA (PGA@nanoflowers) was 207.3 mg/support and the specific activity was 539.1 U/support. In addition, based on the mussel-inspired chemistry, we demonstrated a simple and highly effective strategy to stabilize the enzymes that immobilized on silica nanoflowers by the poly(dopamine) (PDA) coating through in situ polymerization. The effects of pH and temperature on the activity of free PGA, PGA@nanoflowers and immobilized PGA with PDA coating (PDA-coated PGA@nanoflowers) were investigated. The operational stability, storage stability and kinetic properties of the different preparation of PGA were also tested. Compared to free PGA and PGA@nanoflowers, the stabilities of PDA-coated PGA@nanoflowers were all improved significantly. This work demonstrated that the PDA coating presented a new way for surface modification of immobilized enzyme to improve the properties of enzyme. The approach of enzyme@silica hybrid nanoflowers shielding in PDA layer would have great potential in various enzyme immobilization.

Enzyme@silica nanoflower@metal-organic framework hybrids: A novel type of integrated nanobiocatalysts with improved stability

A novel integrated nanobiocatalyst system based on an enzyme@silica nanoflower@metal-organic framework (enzyme@SNF@ZIF-8) structure with improved stability is fabricated for the first time. The versatility of this system is validated using penicillin G acylase (PGA) and catalase (CAT) as model enzymes. The microporous ZIF-8 layer can be controlled by varying the number of ZIF-8 coating cycles, which produces PGA@SNF@ZIF-8 nanobiocatalysts with different ZIF-8 layer thicknesses. After the second ZIF-8 coating cycle, a PGA@SNF@ZIF-8(2) structure with a homogeneous and well-intergrown ZIF-8 layer is formed, which possesses excellent mechanical and chemical stability. Moreover, PGA@SNF@ZIF-8(2) shows improved thermal/storage stability and reusability compared with free PGA and PGA immobilized on silica nanoflowers (PGA@SNF). The obtained CAT-based nanobiocatalysts (CAT@SNF@ZIF-8(2)) also show excellent catalytic performance.

A Facile Preparation Process of Magnetic Aldehyde-Functionalized Ni(0.5)Zn(0.5)Fe₂O4@SiO₂ Nanocomposites for Immobilization of Penicillin G Acylase (PGA).

A facile sol combustion and gel calcination process has been reported for the preparation of core– shell magnetic Zn0.5Fe₂O₄@SiOnanocomposites. The morphology, chemical composition, structure and magnetic property of as-prepared nanocomposites were investigated by XRD, VSM, BET, SEM, and TEM, and the magnetic Ni0.5Zn0.5Fe₂O₄@SiO₂ nanocomposites were characterized with average size of about 25 nm, saturation magnetization of 90.8 Am²/kg and the specific surface area of 67.1 m2/g. The surface of Ni0.5Zn0.5Fe₂O₄@SiO₂ nanocomposites was functionalized with glutaraldehyde to form the aldehyde-functionalized magnetic Ni0.5Zn0.5Fe₂O4@SiO₂ nanocomposites, and penicillin G acylase (PGA) was successfully immobilized onto them. And the immobilized PGA exhibited high effective activity, good stability of enzyme catalyst and good reusability, and could retain 63.5% of initial activity after 12 consecutive operations. The kinetic parameters were determined, and the value of K m for the immobilized PGA (161.7 mmol/L) is higher than that of the free PGA (3.5 mmol/L), while v max (1.626 mmol/min) is also larger than that of the free PGA (0.838 mmol/min), which revealed that the immobilization of PGA onto Ni0.5Zn0.5Fe₂O₄@SiO₂ nanocomposites was an efficient and simple way for preparation of stable PGA.

Immobilization and Characterization of Penicillin G Acylase (PGA) Immobilized on Magnetic Ni₀.₅Zn₀.₅Fe₂O₄ Nanoparticles.

Magnetic Ni₀.₅Zn₀.₅Fe₂O₄ nanoparticles were prepared via the solution combustion process and their microstructure and magnetic properties were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The as-prepared magnetic Ni₀.₅Zn₀.₅Fe₂O₄ nanoparticles are characterized with average grain size of about 20 nm and magnetization of 90.3 Am²/kg. The surface of magnetic Ni₀.₅Zn₀.₅Fe₂O₄ nanoparticles was modified by use of sodium silicate and N-(3-Dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride, and the penicillin G acylase (PGA) was successfully immobilized on the surface-modified magnetic Ni₀.₅Zn₀.₅Fe₂O₄ nanoparticles. The results show that the activity for the immobilized PGA is affected less by pH and temperature than that for the free PGA, and the immobilized PGA exhibits a high effective activity, good stability of enzyme catalyst. This immobilized PGA on magnetic Ni₀.₅Zn₀.₅Fe₂O₄ nanoparticles can be separated from the solution by the external magnetic field for cyclic utilization, and they could retain about 70% of initial enzyme activity after 11 consecutive operations. The kinetic parameters (Km and Vmax) were determined, and the value of Km for the immobilized PGA (204.53 mmol/L) is higher than that of the free enzyme (3.50 mmol/L), while Vmax (1.93 mmol/min) is also larger than that of the free enzyme (0.838 mmol/min).

In situ one-pot preparation of superparamagnetic hydrophilic porous microspheres for covalently immobilizing penicillin G acylase to synthesize amoxicillin

Magnetic hydrophilic porous microspheres were successfully one-pot synthesized for the first time via in situ inverse suspension polymerization of glycidyl methacrylate, N,N′-methylene bisacrylamide and 2-hydroxyethyl methacrylate in the presence of Fe3+ and Fe2+ dispersed in formamide, which were denoted as magnetic Fe3O4-GMH microspheres. The morphology and properties of magnetic Fe3O4-GMH microspheres were characterized by SEM, VSM, XRD, FTIR, and so on. The formamide content had an important influence on the morphology of Fe3O4-GMH, and nearly perfectly spherical Fe3O4-GMH particles were formed when the amount of formamide was 15ml. The diameters of the microspheres were in the range of 100–200μm and Fe3O4-GMH exhibited superparamagnetic behavior with the saturation magnetization of 5.44emu/g. The specific surface area of microspheres was 138.7m2/g, the average pore diameter and pore volume were 15.1nm and 0.60cm3/g, respectively. The content of oxirane groups on Fe3O4-GMH was 0.40mmol/g. After penicillin G acylase (PGA) was covalently immobilized on Fe3O4-GMH microspheres, the catalytic performance for amoxicillin synthesis by 6-aminopenicillanic acid and d-hydroxyphenylglycine methyl ester was largely improved. As a result, 90.1% amoxicillin yield and 1.18 of the synthesis/hydrolysis (S/H) ratio were achieved on PGA/Fe3O4-GMH with ethylene glycol as solvent, but only 62.6% amoxicillin yield and 0.37 of the S/H ratio were obtained on free PGA under the same reaction conditions. Furthermore, the amoxicillin yield and S/H ratio were still kept at 88.2% and 1.06, respectively after the immobilized PGA was magnetically separated and recycled for 10 times, indicating that PGA/Fe3O4-GMH had a very good reusability.

Hydrophilic porous magnetic poly(GMA-MBAA-NVP) composite microspheres containing oxirane groups: An efficient carrier for immobilizing penicillin G acylase

Abstract Magnetic hydrophilic polymeric microspheres containing oxirane groups were prepared by inverse suspension polymerization of glycidyl methacrylate (GMA), N, N′-methylene bisacrylamide (MBAA) and N-vinyl pyrrolidone (NVP) in the existence of formamide, which were denoted as magnetic poly(GMA-MBAA-NVP) microspheres. The magnetic poly(GMA-MBAA-NVP) microspheres were characterized by scanning electron microscopy (SEM), FT-IR spectroscopy, X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and so on. The results showed that poly(GMA-MBAA-NVP) microspheres possessed well spherical shape, narrow size distribution, abundant porous structure, reactive oxirane groups and superparamagnetic properties. Formamide used in the present work served as a modifier, a dispersant and a porogen to form final porous polymer microspheres. The penicillin G acylase (PGA) was covalently immobilized onto the magnetic microspheres through the reaction between the amino groups of enzyme and the oxirane groups on the microspheres for producing 6-aminopenicillanic acid (6-APA). The effects of GMA/NVP ratio and crosslink density on the activity of immobilized PGA were investigated. The highest apparent activity, enzyme loading and coupling yield of immobilized PGA were 821 IU/g, 65.3 mg/g and 42.3% respectively when the mass ratio of GMA/NVP was 1:1 and crosslink density was 60%. Compared with the free PGA, immobilized PGA showed a wider range of pH value and reaction temperature. The relative activity and reaction rate of immobilized PGA remained almost constant after 20 recycles. The magnetic poly(GMA-MBAA-NVP) microspheres would be very promising carriers for immobilizing enzymes in industrial application.

Immobilization of penicillin G acylase on macrocellular heterogeneous silica-based monoliths

A novel material labeled as Si(HIPEs) which possesses macroporosity and mesostructuration was synthesized and functionalized with amino or epoxy groups. The native Si(HIPEs) and functionalized Si(HIPEs) were employed as supports for penicillin G acylase (PGA) immobilization. The effect of pH and temperature on the activity of immobilized PGA was investigated. The reusability, operational stability, storage stability and kinetic properties of the immobilized PGA were examined. Compared with free PGA, the stabilities of immobilized enzyme were improved significantly, especially PGA immobilized on Amino-Si(HIPEs). The excellent reusability of the immobilized PGA will make it useful for potential commercial applications.

An efficient synthesis of ampicillin on magnetically separable immobilized penicillin G acylase

Penicillin G acylase (PGA) was immobilized on the magnetic hydrophilic polymer microspheres with average pore size of 17.1 nm, specific surface area of 128.2 m 2/g and saturate magnetization of 6.4 emu/g. The 96.7% ampicillin yield with 1.60 of the synthesis/hydrolysis (S/H) ratio from 6-aminopenicillanic acid (6-APA) and d-(−)-alpha-phenylglycine methyl ester ( d-PGME) can be achieved using the resultant magnetic biocatalyst in ethylene glycol, where only 82.1% yield with 1.40 of the S/H ratio was obtained using the free PGA under the identical reaction conditions. The immobilized PGA can be separated magnetically and recycled for five times without obvious loss of its catalytic activity.

Hollow silica nanotubes for immobilization of penicillin G acylase enzyme

In this study, porous hollow silica nanotubes (PHSNTs) synthesized via a sol–gel route using nano-sized needle-like CaCO 3 the inorganic templates were employed as a support for immobilization of penicillin G acylase (PGA) biocatalyst. The produced PHSNTs were characterized by BET and transmission electron microscopy (TEM). Effect of various factors such as loading temperature and ratio of carries to free PGA (g/mL) on the catalytic activity of the immobilized PGA was also investigated by unitary factor testing method. The results show that under optimized conditions the relative loading amount and the total activity yield of immobilized enzyme (IME) amounts to 97.20% and 88.80%, respectively. Several advantages, i.e. the rapid immobilization of PGA onto PHSNTs, the high tolerability to the pH, the less sensitivity to the temperature and the improved storage stability render PHSNTs potential support materials for enzyme immobilization.