Enzymes temperature influence

At the start of optimization of the reaction system, suitable values for pH and temperature have to be chosen as a function of the properties of the reactants and enzymes. Fortunately, most enzyme reactions operate in a narrow band with respect to pH value (7-10) and temperature (30-50 °C). The initial substrate concentration and, in the case of two-substrate reactions, the stoichiometric ratio of the two reactants, have to be selected. The selected enzyme concentration influences both the achievable space-time-yield as well as the selectivity in the case of undesired parallel or consecutive side reactions. In the case of multi-enzyme systems, the optimal activity ratio has to be found. The activity and stability of all the enzymes involved have to be known as a function of the reaction conditions, before the kinetic measurements are made. Enzyme stability is an important aspect of biocatalytic processes and should be expressed preferably as an enzyme unit consumption number, with the dimension unit of activity per mass of product (such as mole, lb, or kg). In multi-enzyme systems the stability of all the enzymes has to be optimized so that an optimal reaction rate and space-time-yield result. 

Temperature influence at pressures from 80 bar to 300 bar was the same as at atmospheric pressure. Optimal temperature for esterification was 50°C. The enzyme is less active below and above this temperature. 

Figure 5. Conceptual model showing how temperature influences the effects of different wavelengths of solar radiation on some components of living organisms ( + ) but not others (0). The nature of the + effects (positive or negative) will depend on the temperature optimum of the enzyme system involved. The width of the arrows approximates the strength of the effects.

The catalytic activity of enzymes is influenced by numerous factors. The most important are substrate concentration, enzyme concentration, temperature, and pH. 

Enzymes are involved in many of the chemical reactions that take place in biological processes. Enzymes generally have high specificity for a given substrate and do not attack closely related substrate molecules. This selectivity of enzyme and their ability to catalyze reactions of substrate at low concentrations are of great use in chemical analysis. The activities of enzymes were influenced by many kinds of factors, for instance, pH, temperature, ionic strength, activators, and inhibitors. By use of activity changes of enzymes between the presence and absence of activator (or inhibitor), one can determine the concentration of the activator (or inhibitor). An... 

As mentioned above, units are defined for particular assay conditions. There are many conditions which must be controlled, including temperature, pH, ionic strength, specific ion concentrations, substrate concentrations, presence of activators, stabilizers, and inhibitors. The role of these factors will be illustrated for various enzymes in later sections. At this point it will merely be mentioned that there are no generalities that describe the effect of varying any of these conditions. Each enzyme must be studied as an individual case some are indifferent to conditions that effect others profoundly, and some environmental changes, as temperature, influence competing phenomena, as rate of catalyzed reaction and rate of enzyme destruction. 

EMCs are generally manufactured from cheese pastes that are made from the cheese of the same type. Additional components such as butterfat or cream may be added to add extra precursors when appropriate. Noncheese ingredients such as MSG, yeast extract, diacetyl, or other flavorants may also be added, but they may have to be declared on the label of the final product. Consistency in this base material is critical to the production of a standardized EMC product. Off-flavors may develop during incubation of the paste/enzyme slurry since the conditions are optimal for microbial growth. Equipment must be sterilized and precautions taken to prohibit miCTobial contamination. Bacterial inhibitors such as nitrates, sorbate, or nicin may be used. Free fatty acids generated by lipase enzymes afford some inhibition. Incubation time and temperature influence enzyme action and must be carefully controlled. 

Temperature influences the growth rate of all microorganisms. As with chemical reactions, it accelerates biochemical reactions. Cellular activity (resulting from all of the involved enzyme activities) and consequently growth vary with temperature according to a bell curve. At the optimum temperature, generation time is the quickest. This curb not only varies with the species and strains but also with the environment in which the bacteria multiply. 

Enzyme Sta.bihty, Loss of enzyme-catalytic activity may be caused by physical denaturation, eg, high temperature, drying/freezing, etc or by chemical denaturation, eg, acidic or alkaline hydrolysis, proteolysis, oxidation, denaturants such as surfactants or solvents, etc. pH has a strong influence on enzyme stabiHty, and must be adjusted to a range suitable for the particular enzyme. If the enzyme is not sufficiendy stable in aqueous solution, it can be stabilized by certain additives a comprehensive treatment with additional examples is available (27). 

Enzymatic reactions are influenced by a variety of solution conditions that must be well controlled in HTS assays. Buffer components, pH, ionic strength, solvent polarity, viscosity, and temperature can all influence the initial velocity and the interactions of enzymes with substrate and inhibitor molecules. Space does not permit a comprehensive discussion of these factors, but a more detailed presentation can be found in the text by Copeland (2000). Here we simply make the recommendation that all of these solution conditions be optimized in the course of assay development. It is worth noting that there can be differences in optimal conditions for enzyme stability and enzyme activity. For example, the initial velocity may be greatest at 37°C and pH 5.0, but one may find that the enzyme denatures during the course of the assay time under these conditions. In situations like this one must experimentally determine the best compromise between reaction rate and protein stability. Again, a more detailed discussion of this issue, and methods for diagnosing enzyme denaturation during reaction can be found in Copeland (2000). 

The Influence of Environmental Factors on Enzyme Kinetics. Because enzymes are proteins, they are unusually sensitive to changes in their environment. This is true not only with regard to variations in inhibitor concentrations, but also with respect to variations in pH and temperature. Most enzymes are efficient catalysts only within relatively narrow ranges of pH and temperature. 

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