Enzyme expression, factors affecting

Specific vanadium-induced alterations in the activity or expression level of components of metabolic pathways are described here. Many of these changes are not caused by alterations in the pathway enzymes themselves but in enzymes and factors involved in regulation, commonly referred to as signal transduction systems. Section 11.3 will discuss the alterations described in this section in the context of general signal transduction processes affected by vanadium. 

Factors Affecting Expression of Drug-Metabolizing Enzymes... 

If a period of gene sharing is the rule, then the evolutionary trajectory for improvement of a new activity will be constrained by a number of factors, including how mutations that enhance the new activity affect the old activity, how critical each activity is for fitness, the degree to which the substrate for each reaction inhibits the other reaction, and the capacity for the cell to adapt to enzymatic deficits by increasing enzyme expression. 

In the growth period of a plant, many environmental factors affect how its genetics will be expressed in its phenotype and, consequently, its composition from a nutritional point of view. Additionally, the genetics themselves affect the eventual composition of the plant. In food and feed, SB are usually processed in some way, and this processing may affect the nutritional aspects of SB or SB products. In recent years, the use of enzymes to treat SBM is on the rise to increase the utilization of its nutrients. 

Enzyme kinetics refers to the quantitative analysis of all factors that determine the catalytic potential of an enzyme. As presented in section 1.3, enzyme activity represents the maximum catalytic potential of an enzyme that is reflected by the initial rate of the catalyzed reaction. Several factors affect the expression of such potential, being the most important the concentrations of active enzyme, substrates and inhibitors, temperature and pH. In the case of insolubilized enzymes or multiphase systems, other variables that reflect mass transfer constraints must be considered. 

Conventionally, reaction rates in enzyme kinetics refer always to initial reaction rates where the maximum catalytic potential of the enzyme is expressed and many factors affecting it (i.e. substrate depletion, accumulation of inhibitory products, enzyme inactivation, reverse reaction) are irrelevant (see section 1.3). The quantification of such effects on that maximum catalytic potential is the subject of sections 3.2, 3.3 and 3.4. 

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