Introduction
Enzymes are biological catalysts that hasten the rate of biochemical reactions in living systems. Without the presence of enzymes, essential reactions would take extremely long times to come to completion. All enzymes are made of proteins and, therefore, require certain conditions for them to exhibit maximum activity (Eisenthal & Danson, 2002). Such conditions include temperature, pH, enzyme concentration, the presence of inhibitors and substrate concentration (Seager & Slabaugh, 2013). PH is the extent of the acidity or alkalinity of a solution, which is influenced by the concentration of hydrogen ions. Different enzymes have various optimum pH, which depends on the enzyme’s biochemical role. This experiment aimed at establishing the effect of hydrochloric acid on the activity of catalase. It was hypothesized that acidic conditions would interfere with the activity of catalase.
Materials and Methods
Three small pieces of liver approximately 1cm3 were placed in three plastic beakers, which were labeled A, B and C. To the first beaker (A), 1cm3 of distilled water was added, whereas 1cm3 of lemon juice was added to the second beaker (B). Nothing was added to the beaker labeled C. About 1 ml of hydrogen peroxide was then added into the three beakers simultaneously. The beakers were observed for effervescence and the formation of bubbles. The time taken during effervescence was measured and recorded.
Results
Table 1: Observations of effect of catalase on hydrogen peroxide
It was noted that the addition of hydrogen peroxide to the pieces of liver led to the formation of bubbles. However, the intensity of bubbles varied in the different beakers. The level of effervescence was high in beakers A and C compared to beaker B. In addition, effervescence stopped in beaker B after a shorter time than in beakers A and C.
Discussion
The pieces of liver contained the enzyme catalase, whose main role was to catalyze the conversion of hydrogen peroxide into oxygen and water during the process of detoxification in the liver. Hydrogen peroxide acted as the substrate for catalase. The reaction took place as shown in the equation H2O2 + catalase→ H2O + O2.
The formation of oxygen was what was observed as bubbles in the course of the reaction.
The addition of hydrochloric acid to the liver in beaker B lowered the pH for catalase. Low pH meant there was an increased concentration of hydrogen ions, which affected the integrity of the hydrogen bonds that held the amino acids in the active site of catalase thereby altering the structure of the active site. The affected active site prevented the formation of enzyme-substrate complexes that were necessary for the conversion of substrate into products.
According to Eisenthal and Danson, the optimum pH for catalase was 7 even though the normal physiological pH was 7.4 (2002). In beaker A, distilled water provided a neutral pH that was essential for the activity of catalase (Eisenthal & Danson, 2002). In beaker C, the physiological pH of the liver was maintained since nothing was added and that was why a lot of bubbles were formed. At these pH (7 and 7.4), the outcome of hydrogen and hydroxyl ions on the active site of the enzyme was such that it allowed the formation of a shape that was most complimentary to that of the substrate (Seager & Slabaugh, 2013).
Conclusion
The results of this experiment corresponded to the hypothesis of the experiment that acidity influenced the activity of enzymes. It was, therefore, concluded that enzymes were essential in vital biochemical reactions and that it was important for them to have optimal conditions for their activity.
References
Eisenthal, R. & Danson, J. M. (2002). Enzyme assays: A practical approach. New York, NY: Oxford University Press.
Seager, S. L. & Slabaugh, M. R. (2013). Chemistry for today: General, organic and biochemistry (8th ed.). Stamford, CT: Cengage Learning.