Topic
Immobilized enzyme
About: Immobilized enzyme is a research topic. Over the lifetime, 15282 publications have been published within this topic receiving 401860 citations.
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TL;DR: Under the optimum conditions, the biosensor based on HRP exhibited a fast amperometric response to H(2)O(2), a good linear response over a wide range of concentration from 0.3 μM to 1.00 mM, and a low detection limit of 0.1 μM based on S/N=3.
102 citations
TL;DR: Optimized derivatization conditions are demonstrated for dimer, tetramer, and hexamer dehydrogenases and nonelectroactive substrates are quantitated through the detection of enzyme-generated NADH by fast scan cyclic staircase voltammetry.
Abstract: Dehydrogenase enzymes are immobilized onto carbon-fiber microelectrode surfaces via avidin-biotin technology and a covalently linked hydrophilic tether. The avidin-biotin coupling strategy allows the selectivity of the electrochemical measurement to be easily changed without reoptimizing the immobilization conditions. Optimized derivatization conditions are demonstrated for dimer, tetramer, and hexamer dehydrogenases. Nonelectroactive substrates (ethanol, glucose-6-phosphate, and glutamate) are quantitated through the detection of enzyme-generated NADH by fast scan cyclic staircase voltammetry (100 V/s). The glutamate dehydrogenase-modified microelectrode possesses a 300-ms response time with a detection limit of 0.5 mM glutamate and a 1-60 mM linear concentration range.
102 citations
TL;DR: The firm interaction between the protein molecules and the silica matrix stabilized the enzymes and the half‐life of sol‐gel‐entrapped acid phosphatase at 70 degrees C (pH 8.0) was two orders of magnitude larger than that of the enzyme in solution.
Abstract: Trypsin and acid phosphatase-containing silica sol-gel glasses were obtained by mixing a solution of an enzyme with polyethylene glycol (PEG) 6000 and tetramethoxy orthosilicate at room temperature, followed by gelation and drying. Activity of the immobilized trypsin toward small substrates, such as N-benzoyl-L-arginine-4-nitroanilide at its Km, for the best preparations equaled that of the soluble enzyme. Polylysine (M(r) less than or equal to 13,000) and aprotinin (M(r) = 6,500) inhibited this activity. Larger polylysines as well as soybean trypsin inhibitor (M(r) = 20,100) were ineffective. The sol-gel-entrapped trypsin activity was stable when sol-gel glasses were incubated at ambient temperature (pH 7.5) for several months. In comparison, trypsin, immobilized in sol-gel glass by surface adsorption and incubated under the same conditions overnight, was completely autodigested. The firm interaction between the protein molecules and the silica matrix stabilized the enzymes. Thus, the half-life of sol-gel-entrapped acid phosphatase at 70 degrees C (pH 8.0) was two orders of magnitude larger than that of the enzyme in solution. Transparent, mechanically and chemically stable bioactive sol-gel glasses may be used for the development of robust on-line biochemical photodetection sensors and for the purposes of chemical catalysis.
102 citations
TL;DR: The β-galactosidase immobilized on the magnetic poly(GMA–MMA) beads resulted in an increase in enzyme stability with time, indicating decreased affinity by the enzyme for its substrate, whereas Vmax values were smaller for the immobilizedβ-galactsidase.
102 citations
TL;DR: In this paper, the synthesis of bare maghemite (γ-Fe2O3) nanoparticles was accomplished by thermal co-precipitation of iron ions in ammonia alkaline solution at harsh reaction conditions, respectively.
102 citations