Enzyme genetically modified

D. C. Naseby and J. M. Lynch, Rhizosphere soil enzymes as indicators of perturbations caused by enzyme substrate addition and inoculation of a genetically modified strain of Pseudomonas fluoreseens on wheat seed. Soil Biol. Bioehem. 29 1353 (1997). 

Each of these steps is carried out by a dedicated enzyme encoded by a distinct gene. There is a rich literature on natural and genetically modified bacterial strains that lack discrete components of the denitrification pathway [ 140]. The... 

New biocatalysts (genetically modified bacteria) could break up cellulose/ hemicellulose, but it is necessary, on one hand, to decrease the cost of enzyme production and, on the other hand, to improve reactor and process technology,... 

The enzyme-catalyzed cyanohydrin reaction offers new and interesting perspectives for the synthesis of different kinds of chiral cyanohydrins, because over the next few years the continuous development of new genetically modified oxynitrilases will be without any doubt of great utility for the preparation of pharmaceuticals. 

Table 3.4 Food enzymes produced by genetically modified microorganisms (Source ...

Very many technical and commercial factors are important such as the utility of the product (cost-benefit relationships), ease of scale-up, the productivity of the process etc. Process design, for instance, involves a series of choices, such as the use of isolated enzyme or intact microorganism, use of free or immobilised cell or enzyme, use of mutant or genetically modified cell, or batch or continuous processing etc. Such choices depend on other factors such as the availability and cost of precursors, product purity required, intended scale of operation and existing skills and equipment available within the Organisation. 

The simplest case to consider would be one where a plant had been genetically modified to make a new protein, a protein without enzyme activity, such as the introduction of the Bt toxin. In this case, the concept of equivalence is typically applied. The case is made that the chemistry of the unmodified plant and modified plant are likely to be so similar that they can be considered to be equivalent. 

Genetically modified starters which super-produce certain enzymes unfortunately, the key enzymes are not yet known. 

Currently, mice have the advantage in being available as genetically modified varieties. They can, therefore, be engineered to express human enzymes, for example. Consequently, they can be used to evaluate the mechanism underlying a toxic effect or to simulate a human in terms of metabolism, for example. 

In some cases using genetic engineering, plant breeders may introduce genes into food crops that encode substances that differ substantially in struclure and funclion front substances currently found in food. Based on current developments, such substances would be expected to be proteins or protein enzymes that modify carbohydrates and fatty acids in the food. In some cases, such substances will require premarket approval as food additives in other cases, the food may require new labeling to properly inform consumers of the new attributes of the food. However, in most cases to date, the substances that occur in food as a result of gene transfer have been safely consumed as food previously or are subslanlially similar to food substances and would not require premarket review by FDA. 

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