Enzymes are proteins that accelerate chemical
reactions and which act on specific molecules called substrates, in order to
produce other molecules known as products. Enzymes have a three dimensional
shape in order to fit perfectly with their substrate. The area on the enzyme
where the substrate connects is called the active site. In order to trigger a
reaction, the enzyme and the substrate have to collide with a sufficient
energy; enzymes do not provide the energy, they just lower the minimum energy
required to start the reaction. The energy known to start the chemical reaction
is called the activation energy.

 

                  Catalase
is an enzyme found nearly in all living organisms. Catalase is a very common
globular protein molecule and has the fundamental job to catalyse the
decomposition of H2O2, Hydrogen Peroxide, into water and
oxygen. Hydrogen peroxide, catalase’s substrate, is a poisonous substance.

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However there are some specific circumstances in which
enzymes will perform their job, three main factors that effect the enzyme’s
activity: pH, substrate concentration and temperature. There is not a perfect
pH which fits best to all enzymes. Many enzymes are  most efficient when the pH is neutral but
other cases, such as the case of pepsin, 
an enzyme in the stomach that requires a particularly acidic pH in order
to work. Temperature is another factor, which affect the enzyme’s activity;
molecules will move faster with higher temperature, increasing the probability
of collision and start the reaction. However if temperatures get to high the
enzyme will be denatured and will lose its three dimensional shape. When an
enzyme loses its three dimensional shape it will also lose its efficiency
because no substrate will fit in the active site.

The last factor which affects the enzyme activity is
the concentration of the substrate. As the concentration of a substrate
increases, the rate of reaction will increase as well.

I will remove from raw potato 6 cylinders and cut them
into 6 different sizes. I want to investigate how the different sizes of the
tuber react to hydrogen peroxide at a certain temperature. The temperature will
not overcome the limit where the enzyme would denature. I will repeat this
experiment 3 times with each time other 6 raw potato cylinders.

 

I chose this topic because I enjoyed very much the
topic on enzymes as they are the natural catalysts which keep us alive by
performing their perfect job. However I was curious about the reaction between
catalase and hydrogen peroxide and I wanted to understand if there is a
significant change in the reaction time if the enzyme’s surface area is increased
or if they are independent from one another.