Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:6.3.4.6 (urease)
 7,490 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Three types of organic polymers and bead-shape silica gels were activated by graft polymerization of 2,3-epoxypropyl methacrylate; in some cases, epoxide groups on the support surface were modified to NH2 groups. Eight active matrices so obtained were assessed as supports for immobilized enzymes using peroxidase, glucoamylase and urease. The immobilization yield of protein and specific activities of enzymes were better with supports containing NH2 groups than with those containing epoxide spacer arms. Maximum enzyme immobilization and storage stabilities were obtained with silica-gel beads activated by graft polymerization of 2,3-epoxypropyl methacrylate. With all eight matrices tested, the immobilized enzymes showed good stability with not less than 82% of the original activity persisting after 28 days. The developed matrices have potential for use in process-scale biotechnological operations.
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PMID:Immobilization of enzymes to porous-bead polymers and silica gels activated by graft polymerization of 2,3-epoxypropyl methacrylate. 136 57

pH and temperature play critical roles in multistep enzymatic conversions. In such conversions, the optimal pH for individual steps differs greatly. In this article, we describe the production of glucoamylase (from Aspergillus oryzae MTCC152 in solid-state fermentation) and glucose isomerase (from Streptomyces griseus NCIM2020 in submerged fermentation), used in industries for producing high-fructose syrup. Optimum pH for glucoamylase was found to be 5.0. For glucose isomerase, the optimum pH ranged between 7.0 and 8.5, depending on the type of buffer used. Optimum temperature for glucoamylase and glucose isomerase was 50 and 60 degrees C, respectively. When both the enzymatic conversions were performed simultaneously at a compromised pH of 6.5, both the enzymes showed lowered activity. We also studied the kinetics at different pHs, which allows the two-step reaction to take place simultaneously. This was done by separating two steps by a thin layer of urease. Ammonia generated by the hydrolysis of urea consumed the hydrogen ions, thereby allowing optimal activity of glucose isomerase at an acidic pH of 5.0.
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PMID:Effect of pH on simultaneous saccharification and isomerization by glucoamylase and glucose isomerase. 1239 22

A "smart" biofuel cell switchable ON and OFF upon application of several chemical signals processed by an enzyme logic network was designed. The biocomputing system performing logic operations on the input signals was composed of four enzymes: alcohol dehydrogenase (ADH), amyloglucosidase (AGS), invertase (INV) and glucose dehydrogenase (GDH). These enzymes were activated by different combinations of chemical input signals: NADH, acetaldehyde, maltose and sucrose. The sequence of biochemical reactions catalyzed by the enzymes models a logic network composed of concatenated AND/OR gates. Upon application of specific "successful" patterns of the chemical input signals, the cascade of biochemical reactions resulted in the formation of gluconic acid, thus producing acidic pH in the solution. This resulted in the activation of a pH-sensitive redox-polymer-modified cathode in the biofuel cell, thus, switching ON the entire cell and dramatically increasing its power output. Application of another chemical signal (urea in the presence of urease) resulted in the return to the initial neutral pH value, when the O(2)-reducing cathode and the entire cell are in the mute state. The reversible activation-inactivation of the biofuel cell was controlled by the enzymatic reactions logically processing a number of chemical input signals applied in different combinations. The studied biofuel cell exemplifies a new kind of bioelectronic device where the bioelectronic function is controlled by a biocomputing system. Such devices will provide a new dimension in bioelectronics and biocomputing benefiting from the integration of both concepts.
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PMID:Biofuel cell controlled by enzyme logic network--approaching physiologically regulated devices. 1935 82