Essay Enzyme Substrate Complex

Both low pH levels and high pH levels produced a low amount of catalase activity.

Of the many functions of proteins, catalysis is by far the most vital. When catalysis is not present, most reactions in the biological systems take place very slowly to produce at an adequate pace for metabolising organism. The catalysts that take this role are called enzymes. Enzymes are the most efficient catalysts; they can enhance rate of reaction by up to 1020 over uncatalysed reactions. (Campbell et al, 2012).

40 mL of a concentrated solution of sucrose was prepared at 200mg/mL. Using appropriate dilutions of the stock, 11 solutions including a control solution were made in plastic tubes. The enzyme reaction with sucrose was run in 2 mL volume at room temperature in water. The enzyme constituted half the volume of the stock solution. The substrate was added to the enzyme in order to start the reaction. Each reaction ran for 5 min after which 2 mLs of DNS reagent was added. The solution was boiled for 10 min and the results were read using a spectrophotometer.

pH - Enzymes also have an optimum pH level. The pH of a solution affects the enzyme's secondary and tertiary structures. These bonds make the shape of an enzyme's active site. So, if these bonds are broken, the shape of the active site changes and is distorted. If there is no active site, there is no reaction resulting in no products. If the enzyme is put in a pH that is very different from the optimum pH, it can cause the enzyme to denature.

State the optimum pH for sucrase activity and how sucrase activity changes at more acidic and alkaline pH values. The optimum pH for sucrase activity is 6 and decrease with greater acidic and alkalline values.

Lab six requires students to observe the effects of pH and enzyme concentration on catecholase activity. Enzymes are organic catalysts that can affect the rate of a chemical reaction depending on the pH level and the concentration of the enzyme. As pH comes closer to a neutral pH the enzyme is at its greatest effectiveness. Also at the absorbance of a slope of 0.0122 the enzyme is affected greatly. The pH effect on enzymes can be tested by trying each pH level with a pH buffer of the same pH as labeled as the test tube and 1mL of potato juice, water, and catechol. This is all mixed together and put in the spectrophotometer to test how much is being absorbed at 420nm. As the effect on enzyme concentration can be tested almost the same way. This part of the exercise uses different amounts of pH 7-phosphate buffer and potato juice, and 1mL of catechol mixed together in a test tube. Each substance is put in the spectrophotometer at a wavelength set tot 420nm. The results are put down for every minute up to six minutes to see how enzyme concentration affects reaction rate. The results show that the pH 8 (0.494) affects the enzyme more than a pH of 4 (0.249), 6 (0.371), 7 (0.456), and 10 (0.126). Also the absorbance is greatest at a slope of 0.0122 with test tube C that has more effect on the reaction rate, than test tube A, B, and D.

Question: How does changing enzyme concentration or temperature affect the reaction time of enzyme activity?

If different temperatures are used to catalyze enzyme activity, then the lowest temperature would produce the quickest reaction rate because enzymes can become denaturized at higher temperatures

The null hypothesis for the first experiment was that substrate concentration would have no effect on the reaction rate. It was hypothesized that the reaction rate would increase with rising substrate concentrations, until all active sites were bound. The null hypothesis for the second experiment was that temperature would not have an effect on reaction rates. It was hypothesized that until the enzyme is denatured, as temperature increased, so would the reaction rate.

Changes in pH also alter an enzyme’s shape. Different enzymes work best at different pH values. The optimum pH for an enzyme depends on where it normally works. For example, intestinal enzymes have an optimum pH of about 7.5 whereas enzymes in the stomach have an optimum pH of about 2.

Enzymes are a key aspect in our everyday life and are a key to sustaining life. They are biological catalysts that help speed up the rate of reactions. They do this by lowering the activation energy of chemical reactions (Biology Department, 2011).

Which enzyme shows the greatest change in its rate of action with the least change in pH?

We did this to test which test tube would contain the highest concentration of glucose. What we wanted to know was if the lactase would affect the function of the enzyme. Our hypothesis is the lactase functions within a narrow pH and that will change in pH would affect the function of the enzyme. We predict that if we change the environmental factors it will have an effect the function of the enzyme if the pH is outside the range in its optimum activity. Our hypothesis was then proven because the reaction only occurred in a neutral and acidic state of pH, not basic. Which means the enzymes prime ability to function is a neutral, and acidic pH range.

The maximum rate of reaction found in lab was . The two rates are close in value. 2. pH affects the enzyme-catalysed reaction rates because all enzymes have an optimal pH range in which they can function (Royal Society of Chemistry, 2004). If the pH of their environment transgresses too far from their optimal pH, the enzyme will begin to denature.

And when the pH level drops, or gets higher than 7-8, the substance will disrupt the hydrogen bonds between the protein chains. Furthermore, when this happens near the active site, the structure or shape of the active site changes and the substrate won’t fit perfectly. Therefore, not all of the catalase will be catalyzed and the reaction rate will decrease. If this continues, there will be a point where the reaction rate is