Cells, enzymes

This enzyme is of wide occurrence in bacteria where it is concerned with the reduction of nitrate and CO2 as well as sulphur. Methods for its estimation depend on measuring some activity of hydrogenase by (a) dye reduction (benzyl viologen or methylene blue), (b) isotopic exchange and (c) evolution of molecular hydrogen. Interpretation of quantitative results is difficult due to the complex relationship between the enzyme cell structure and the particular method selected. ... 

Polyamines and their ammonium salts have been of interest because they are known to have potential applications as chelating agents (1-3), ion exchange resins (4-6), flocculants (7,8), and other industrial uses (9). Recent biomedical applications have constituted another important use of polymeric amines they have been investigated for use as biocompatable materials, polymeric drugs, immobilization of enzymes, cell-culture substratum and cancer chemotherapeutic agents (10-12). 

Most of the known microorganisms to be active for BDS (by the date that patent [408] was introduced), were considered in this invention. Furthermore, their mutational or engineered derivatives, enzymes, cell-free extracts, recombinant enzymes, recombinant DNA, plasmids, vectors, and fragments were also incorporated in the intellectual property document. The mentioned operating conditions regard ambient temperature, mechanical agitation and a 1 9 biocatalyst/petroleum ratio. 

Dierks, T., Schmidt, B., Borissenko, L. V. et al. Multiple sulfatase deficiency is caused by mutations in the gene encoding the human Ca-formylglycine generating enzyme. Cell 113 435-444, 2003. 

Ballesteros et defined immobilized biocatalysts as enzymes, cells or organelles (or combinations of these) which are in a state that permits their reuse . Enzyme immobilization represents only a small part of this field, but is the most commonly employed in pharmaceutical production. 

Biological catalysts in the form of enzymes, cells, organelles, or synzymes that are tethered to a fixed bed, polymer, or other insoluble carrier or entrapped by a semi-impermeable membrane . Immobilization often confers added stability, permits reuse of the biocatalyst, and allows the development of flow reactors. The mode of immobilization may produce distinct populations of biocatalyst, each exhibiting different activities within the same sample. The study of immobilized enzymes can also provide insights into the chemical basis of enzyme latency, a well-known phenomenon characterized by the limited availability of active enzyme as a consequence of immobilization and/or encapsulization. 

Figure 3.8 — (A) Biosensors used in different FI manifolds to perform reaction-rate measurements (I) stopped-flow manifold (II) iterative flow-reversal system (III) open-closed configuration S sample B buffer P pump IV injection valve PC personal computer IMEC immobilized enzyme cell D detector W waste SV switching valve. (B) Types of recordings obtained by using the three types of biosensors and measurements to be performed on them in order to develop reaction-rate methods. (Reproduced from [50] with permission of Elsevier Science Publishers).

Yl. Yuan, J., Shaham, S., Ledoux, S., Ellis, H. M., and Horvitz, H. R., The C. elegans cell death gene ced-3 encodes a protein similar to mammaUan interleukin-1 beta-converting enzyme. Cell 75, 641-652(1993). 

Extracellular enzyme Cell removal (solid liquid separation) Centrifugation Filtration... 

Table 11.1 below gives a non-exhaustive view of the catalyzed reactions tested at the solid / gas interface, using purified enzymes, cell extracts, or whole cells. 

We may define the biological system undergoing study as a biocomponent (e.g. enzyme, cell, tissue, organism) which is interacting with a bioactive substance. In... 

The principle of the mass transport of substrates/nutrients into the immobilized enzyme/cells, through a solid, porous layer (membrane, biofilm) or through a gel layer of enzyme/cells is the same. The structure, the thickness of this mass-transport layer can be very different, thus, the mass-transport parameters, namely diffusion... 

Web-based interface to manually enter low-throughput enzyme, cell, PK/ADME/Tox and animal data... 

A sensitized electrode is a composite device that combines a membrane reactor and a primary electrode. The membrane reactor converts a specific analyte into products that are measurable by the primary electrode. Membrane reactors containing immobilized enzymes, cells, or neutral carriers are capable of very selective conversion of sugars, amino acids, organic acids, and alcohols, and... 

Hughes AL, Powell DW, Bard M et al (2007) Dapl/PGRMCl binds and regulates cytochrome P450 enzymes. Cell Metab 5 143-149... 

In addition to purified and modified enzymes, cell preparations containing a set of enzymes catalyzing an entire sequence of reactions have been successfully immobilized. At present, a step ahead can be registered in the case of cofactor-... 

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