Enzymes temperature change effect

The exposure of plants to low temperatures induces many changes in physiological and biochemical parameters. Many studies have attempted to investigate the relationship between low temperature and enzyme activities. The effects of low temperature treatments on the protein levels and on activity of some plant cell enzymes are reported in Table 1. 

The graph of enzyme activity as a function of pH is somewhat similar to the behavior as a function of temperature (see > Figure 10.8). Notice in Figure 10.8 that an enzyme is most effective in a narrow pH range and is less active at pH values lower or higher than this optimum. This variation in enzyme activity with changing pH may be due to the influence... 

A simple procedure reported for the isolation of jack-bean a-D-mannosidase was based on affinity chromatography on agarose-immobilized benzidine. The influence of substituents on the hydrolysis of substituted phenyl a-D-mannopyranosides by a-D-mannosidase from Medicago sativa seeds has been investigated. As indicated by structure-activity relations, the electronic effect of the substituent has an influence on the rate of formation of the intermediate D-mannosyl-enzyme complex. This effect depends not only on the nature of the substituent, but also on its position meta or para) and on the temperature of the experiment. Hammett-type linear free energy relationships show that the reaction constant p changes its sign at ca. 27 °C. Substrates... 

BC can also be employed as support for enzymes and cells immobilization. Glucoamylase has been immobilized in BC beads (0.5-1.5 mm) which demonstrated to increase its stability towards pH and temperature changes [67]. Wine yeast has also been immobilized in BC, showing higher metabolic activity and resistance to imfavor-able conditions during wine fermentation in comparison with non-immobilized yeasts. In addition, the application of immobilized yeast to repeated batch fermentation in wine-making enhances the economic effectiveness of the production-line because of the cost reduction in inoculum preparation and the simple separation of yeast at the end of the fermentation [68, 69]. 

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