Immobilized enzyme

About: Immobilized enzyme is a research topic. Over the lifetime, 15282 publications have been published within this topic receiving 401860 citations.

A new support for the immobilization of penicillin acylase

Abstract: Mesoporous MCM-41 having well ordered long-range structure, large pore diameters, narrow pore-size distribution, high pore volume and specific surface area has been synthesized. The surface of MCM-41 has an abundance of weakly acidic hydroxyl groups. Assay results show that MCM-41 is a more effective support for the immobilization of Penicillin Acylase (PA) than many of other supports due to its structural and surface characteristics. PA can be immobilized on MCM-41 through either direct immobilization or covalent coupling. The former gives higher activity of IME than the later. In the direct immobilization, PA molecules are immobilized on MCM-41 through the hydrogen-bonded interaction between hydroxyl groups of MCM-41 and carbonyl or amino groups in the PA molecule.

Multi-enzyme membrane electrodes for determination of creatinine and creatine in serum.

Abstract: An enzyme electrode system for the determination of creatinine and creatine was developed by utilizing three enzymes: creatinine amidohydrolase (CA), creatine amidinohydrolase (Cl), and sarcosine oxidase (SO). These enzymes were co-immobilized onto the porous side of a cellulose acetate membrane with asymmetric structure, which has selective permeability to hydrogen peroxide. Two kinds of multi-enzyme electrodes were constructed by combining a polarographic electrode for sensing hydrogen peroxide and an immobilized CA/Cl/SO membrane or Cl/SO membrane for creatinine plus creatine or creatine, respectively. The multi-enzyme electrodes responded linearly up to 100 mg of creatinine and creatine per liter in human serum. Response time was 20 s in the rate method and the detection limit was 1 mg/L. Only 25 microL of serum sample is required. Analytical recoveries, precisions, and correlations with the Jaffe method were excellent, and the multi-enzyme electrodes were sufficiently stable to perform more than 500 assays. No loss of activity of immobilized enzymes was observed after nine months of storage at 4 degrees C in air.

Modified alginate matrices for the immobilization of bioactive agents.

Abstract: Bioactive agents (catalase - an enzyme, and nisin - a bacteriocin) were covalently immobilized on alginate activated with sodium periodate (oxidatively converting 2,3-dihydroxy groups into dialdehyde residues), followed or preceded by ionotropic gelation. For the same protein coupling yield, the retained enzyme activity of the immobilized enzyme (ImE) can be markedly increased by diminishing the bead diameter, a phenomenon that illustrates the role of substrate/product diffusion through the bead gel layer. When the amount of enzyme introduced for coupling was about 15 mg/100 mg of support and the bead diameter was about 100 microm, a high retained specific activity (95-98%) was obtained. Diffusion phenomena can be markedly decreased by enzyme immobilization on the surface of microbeads (obtained by gelation of activated alginate prior to immobilization). In this case, the retained activity was approx. 75% of that of the free enzyme. A slightly higher K (m) value of ImE suggested that the enzyme-substrate affinity was almost maintained. The profiles of ImE activities at various pH values, at various temperatures and when undergoing proteolysis showed a overall higher stability for the immbolized than that for the free enzyme. Nisin immobilized on the microbead surface, when submitted to proteolysis, conserved its bacteriocin activity, strongly inhibiting the growth of Lactobacillus sake when subjected to an agar spot test, whereas free nisin totally lost its activity.

Characterization of immobilization of an enzyme in a modified Y zeolite matrix and its application to an amperometric glucose biosensor.

Abstract: A new approach to construct an amperometric biosensor is described. Without using bovine serum albumin−glutaraldehyde, glucose oxidase (GOx) was immobilized on a dealuminized Y zeolite (DAY)-modified platinum electrode to construct a glucose sensor. The large specific surface area of the zeolite substrate resulted in high enzyme loading. The immobilized GOx in this manner was stable and could maintain its high activity for at least 3 months. The interactions between the zeolite and the enzyme were investigated by means of Fourier transform infrared spectra, and the pore distribution and the surface acid property of DAY were preliminarily studied. The results showed that the hydrophilic property and the existing mesopores of DAY played important roles in the enzyme immobilization. This resulting biosensor exhibited good reproducibility and selectivity, owing to the uniform pore structure and unique ion-exchange property of the zeolite. The biosensor responded rapidly to glucose in the linear range from 2.0...