Measuring the reactions of the enzymes catecholase in different levels of pH in different tempereture - Lab Report Example

Measuring the reactions of the enzymes catecholase in different levels of pH in different tempereture Introduction Enzymes are biological catalysts which speed up chemical reactions. These enzymes have active sites which bind to the substrates thereby converting the substrate into the final products at a faster rate due to the lowering of the energy of activation. Enzymes are however affected by environmental factors such as pH and temperature and chemicals. Many enzymes work well in a narrow range of pH.

A change in pH may alter the three dimensional structure of the enzyme due to formation or breakage of covalent bonds within the enzyme. A change in the structure of the enzyme may affect the enzymes binding ability and consequently its activity. Temperature rise of about 10oC normally doubles or triples the rate of enzymatic reactions. However beyond the optimum temperature the enzyme activity decreases. If catecholase activity is minimally affected at different temperatures and pH then it can be hypothesized that it has a large range of optimal activity.

The aim of this experiment was to test the effect of temperature and pH on the enzymatic activity of catecholase.MethodsThe effect of catecholase enyme at different temperatures, 0 and 37oC were tested at different levels of pH 2, 4, 7 and 12. Three tubes for each pH were set up and labelled A, B and C. To three tubes in each pH 3ml of the pH solution was added and 2ml of banana extract (substrate). To two tubes 1ml of the enzyme (potato extract) was added while the third tube the enzyme was not added and acted as the control.

The test tubes were then shaken and put in the appropriate temperature and the optical density measured after three minutes. ResultsThe reaction rate was the highest at all temperatures at pH 7. At room temperature the reaction rate was the highest in the tube without the enzyme. pH 4 and 12 had the lowest reaction rates at all temperatures. The reaction rates were highest between 0oC and room temperature in the presence of catecholase and lowest at 0oC without the enzyme.DiscussionCatechol oxidase (catecholase) is a polyphenol oxidase enzyme present in many plants (Aniszewski et al. 2008). It is responsible for catalysing the reaction between oxygen and hydroxylated benzenes leading to the production of quinines and water.

The enzyme mediated reaction rate was the highest at physiological pH and at temperatures between zero and room temperature. This shows that the enzyme has a large range of optimal temperatures. However, it has a narrow range of optimal pH. The narrow pH range during which catecholase activity was the highest is due to the effect of pH on the redox behaviour of catecholase activity (González-Sebastián et al. 2010)Literature citedAniszewski T, Lieberei R and Gulewicz K. 2008. Research on catecholases, laccases and cresolases in plants.

Recent progress and future needs. Acta Biologica Cracoviensia Series Botanica 501: 7–18.González-Sebastián L, Ugalde-Saldívar VM, Mijangos E, Mendoza-Quijano MR, Ortiz-Frade L, Gasque L. 2010. Solvent and pH effects on the redox behavior and catecholase activity of a dicopper complex with distant metal centers. J Inorg Biochem. 104(10):1112-8.