Effect On Enzyme Concentration On Catalysis Biology Essay


Enzymes may be considered as one of the most important proteins of the human body. In particular an enzyme such as amylase, which breaks down carbohydrates, work by means of surface catalysis; the surface of the enzyme enables other molecules to react in a manner they would not be able to without the surface of the enzyme present. It is said that enzymes achieve this by lowering the amount of activation energy needed for anabolic reactions; this allows these reactions to occur as a catabolic reaction would. "Enzymes are generally large proteins that consist of several hundred amino acids, and often contain a non-proteinaceous group otherwise known as a prosthetic group of which is important in the actual catalysis. In an enzyme catalyzed reaction, the substance to be acted upon, or substrate, binds to the active site of the enzyme. The enzyme and substrate are held together in an enzyme substrate complex by hydrophobic bonds, hydrogen bonds, and ionic bonds." (Nichols and Cholewiak, 1991). Enzymes are not only important because they keep the metabolic pathway free of congestion but the are also key in digestion, also they are needed to perform an infinite number of task within the human cellular system. Enzyme productivity like many other things our bodies tend to vary based on outside factors. Environmental parameters such as temperature, pH, and substrate concentration such as starch affect the rate of enzymatic catalysis in our body.

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The human body is perhaps the greatest test of enzyme adaptability. It uses enzymes in countless ways, and in numerous conditions thus it is important that we understand the effects of its environmental parameters. Upon the completion of this experiment it was found that when temperature and pH were help constant the activity of an enzyme is determined by the relative concentration of the enzyme and its substrate, starch in this case. Specifically, it was found that a 1% starch solution resulted in the highest rate of enzyme activity. This was determined by the use of iodine which is a starch indicator; the time of which each concentration of starch reacted was also noted (the appearance of a light yellow brown colour). Test tube A which had the highest starch concentration reacted within a minute, test tube B having the second highest starch concentration reacted within five minutes, while test tube C having the third highest starch concentration reacted within seven minutes and lastly test tube D having the least amount of starch concentration took eight minutes to react. If there is an excess of substrate, the rate of catalysis is directly proportional to the enzyme concentration. Based on the results it can said that if the enzyme concentration is kept constant, as it was in this experiment, then the rate of reaction is directly proportional to the amount of substrate present. Thus an increase in substrate starch causes an increase in enzyme catalysis. However this is only up unto the point when all enzyme molecules are utilized or saturated and will no longer increase in rate of productivity.

The result obtained from this experiment supported the hypothesis on amylase activity under experiment conditions inclusive of constant temperature and pH with varying substrate concentration, likewise the hypothesis of Jensen et al., 1997; Skrabanja & Tufvesson, 2000 but under different experimental conditions.


-Wash dropper after every use as this may lead to inaccurate results.

-Ensure that the amount of reagents used does not exceed that required.


-We were unable to conduct a much larger experimental group which would have been needed in order to find amylase's optimal catalysis condition, or saturation point.

Source of error

-When conducting the experiment on test tube B there was time delay by the fact that time was not properly compensated when all parts of the solution could not be added by one person simultaneously. However this was not severe to the extent where we had inaccurate results, but test tube B may have reacted faster than within the five minutes.


In concluding, it can be said that if the substrate concentration was to be increased then there will be an increased in enzymatic activity. This experiment could have been improved if we had conducted a larger experimental group which is needed in order to find the optimal condition of amylase. Never the less the experiment was a success and we have acquired our aim, likewise proved to be in one with our hypothesis; which states that the rate of reaction is directly proportional to the amount of substrate present. Thus an increase in the substrate starch cause and increase in enzyme catalysis.

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