Enzyme activity

Factors affecting enzyme activity pdf

Most enzymes function between a pH of 6 and 8; however pepsin in the stomach works best at a pH of 2 and trypsin at a pH of 8. Discontinuous assays[ edit ] Discontinuous assays are when samples are taken from an enzyme reaction at intervals and the amount of product production or substrate consumption is measured in these samples. At this point, so much substrate is present that essentially all of the enzyme active sites have substrate bound to them. In this lab, you can quantify how different conditions affect enzyme function, by assessing the reaction rate, the amount of product made, per unit time. Specific activity is equal to the rate of reaction multiplied by the volume of reaction divided by the mass of total protein. The rate of an enzyme-catalyzed reaction increases with an increase in the concentration of an enzyme. This more sophisticated model relies on the fact that molecules are flexible because single covalent bonds are free to rotate.

Measuring Enzyme Function One method used by scientists to study the effects of different conditions on enzyme function is to quantify the reaction rate, which is how fast the enzyme is catalyzing the reaction.

Figure Each type of enzyme can only bind to one or a few specific substrates, therefore, there is a vast diversity of enzymes, all with distinct functions.

Methods Enzymol.

enzyme activity pdf

The enzyme that you'll work with in this lab is turnip peroxidase. These assays are very general, since many reactions involve some change in heat and with use of a microcalorimeter, not much enzyme or substrate is required.

Once the baseline reaction rate has been established, it can be used as reference point for other conditions. Upon substrate binding, the enzyme changes shape slightly in a way that allows the chemical reaction to happen more readily, thus reducing the activation energy of the reaction.

enzyme activity experiment

All the reactions that occur in living organisms require high activation energy to take place. Concentration of Substrate In the presence of a given amount of enzyme, the rate of an enzymatic reaction increases as the substrate concentration increases until a limiting rate is reached, after which further increase in the substrate concentration produces no significant change in the reaction rate part a of Figure Inhibitors that attach to other parts of the enzyme molecule, perhaps distorting its shape, are said to be non-active site-directed or non competitive.

Radiometric[ edit ] Radiometric assays measure the incorporation of radioactivity into substrates or its release from substrates. Because the measurements are carried out for a very short period and because of the large excess of substrate, the approximation that the amount of free substrate is approximately equal to the amount of the initial substrate can be made.

Effects of Temperature: All enzymes work within a range of temperature specific to the organism. In these experiments, reaction behaviour is tracked during the initial fast transient as the intermediate reaches the steady-state kinetics period.

Enzyme activity
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Factors Affecting Enzyme Activity (Introduction to Enzymes)