Determination of the activation energy of an enzyme catalysed reaction
In this practical the aim for this experiment was to find out the catalytic power of alkaline phosphate, as well as the rate of reaction and the activation energy of p-nitrophenol phosphate.
Enzymes are biological molecules that catalyse a chemical reaction. ‘Enzymes work by lowering the activation energy of a chemical reaction making it easier to proceed’ . This allows molecules to have more energy therefore it makes them collide so that product can be formed much quicker. In order for enzymes to work properly the activation energy must be exceeded first.
Enzymes are described as the lock and key complex. They have an active site which is
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This is clearly shown on the graph. This is because the concentration of p-nitrophenol increases as the absorbance in the light passing through the different dilutions has a stronger absorbance because the colour of the dilutions gets darker and stronger. From the graph and table for experiment b) The time increased the concentration also increased for both temperatures. As the enzyme reacting with the p-nitrophenyl phosphate this is the substrate and the enzyme needs the binding site so that it can form a product. ‘A nonspecific inhibition affects all enzymes in the same way. Non-specific methods of inhibition include any physical or chemical change which ultimately denatures the protein portion of the enzyme and are therefore irreversible.’ Towards the start the concentration starts to level off in the graph due to the NaOH as it is the inhibitor and it blocks the binding site of some enzymes. The concentration for p-nitrophenol phosphate at 35° is higher than that of 25°. This is due to the fact that the temperature increases the collision which therefore increases the rate of reaction therefore making the enzymes react faster. As the temperature increases the enzyme