Immobilization of glucose oxidase: A comparison of entrapment and covalent bonding

Abstract

Glucose oxidase was immobilized onto poly(2‐hydroxyethyl methacrylate) (pHEMA) membranes by two methods: by covalent bonding through epichlorohydrin and by entrapment between pHEMA membranes. The highest immobilization efficiency was found to be 17.4% and 93.7% for the covalent bonding and entrapment, respectively. The Km values were 5.9 mmol dm−3, 8.8 mmol dm−3 and 12.4 mmol dm−3 for free, bound and entrapped enzyme, respectively. The Vmax values were 0.071 mmol dm−3 min−1, 0.067 mmol dm−3 min−1 and 0.056 mmol dm−3 min−1 for free, bound and entrapped enzyme. When the medium was saturated with oxygen, Km was not significantly altered but Vmax was. The optimum pH values for the free, covalently‐bound and entrapped enzyme were determined to be 5, 6, and 7, respectively. The optimum temperature was 30°C for free or covalently‐bound enzyme but 35°C for entrapped enzyme. The deactivation constant for bound enzyme was determined as 1.7 × 10−4 min−1 and 6.9 × 10−4 min−1 for the entrapped enzyme.

The Properties of Covalently Immobilized Trypsin on Soap‐Free P(MMA‐EA‐AA) Latex Particles

“…These phenomena are caused by several factors such as protein conformational changes induced by attachment to the support, steric hindrance and diffusional effects. [31,32] …”

“…[39][40][41] When the enzyme is immobilized, the support itself may change the pH value around the catalytic active site. [32] This effect is known as the Donnan partitioning effect [42] and is directly related to the physical structure and chemical composition of the supporting material which induces electrostatic or hydrophobic interactions between the matrix and the molecular species dissolved in the solution. These interactions alter the microenvironment in which the enzyme actually operates.…”

Enhanced wettability of a SU-8 photoresist through a photografting procedure for bioanalytical device applications

“…Polymeric HEMA (pHEMA) is known for its biocompatibility [14] and as such is found as the base material in soft contact lenses. Because of this, the transport of water and oxygen through pHEMA hydrogels has been studied [15] and it has subsequently attracted attention as a matrix for use in enzyme immobilization strategies [16][17]. PEG is a well studied polymer frequently used to improve its biocompatibility and wetting properties of various materials [18].…”

Covalent Immobilization of Glucose Oxidase on Well-Defined Polymer-Silicon Wafer Hybrids via Surface-Initiated Raft-Mediated Process

“…Because the active conformation of the enzyme through covalent immobilization is stabilized by multipoint bond formation between the substrate and the enzyme molecules, covalent immobilization often result in the highest stabilization effect on enzyme activities. 36,37 Moreover, the stability of immobilized GOD also depends on the coupling method. For example, the stability of the immobilized enzyme via a 1,3-bifunctional aromatic coupling agent was reduced, which may results from the conformation deformation of the active enzyme and the loss in the multipoint binding ability of the enzyme.…”