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Meera Patel
Enzyme lab
6/3/2013

Assignment 1 :- Effect of Temperature on Invertase Activity, Determining the Starting Velocity. Enzyme is the fastest known catalyst. They increase the velocity and rate of reactions in living cells. Diverse range of proteins works as enzyme with their specific temperature point, pH etc. Enzymes react with the molecules known as substrates. Binding site of an enzyme and a substrate is known as active site. The amount of enzyme present in a reaction is measured by the activity it catalyzes. The relationship between activity and concentration is affected by many factors such as temperature, pH, etc. Though enzymes are important for biological reactions, certain factors play an important role in the activity. Enzymes works at their optimum temperatures and pH condition, that means the point where the activity is highest. If the factor goes above the optimum values, proteins get denatured due to the alterations in the bonds like hydrogen bonds and Van Der Waals attractions. Enzyme kinetics is greatly influenced by the substrate concentration and velocity. The enzymatic catalyzing begins by the process of binding of an enzyme to a substrate and forming the enzyme substrate complex called ES. These types of reactions are either reversible or irreversible. Hypothesis: The enzyme becomes denatured at high temperatures. That means that the chemical bond holding the structure together break down, so the shape of the enzyme changes and can no longer operate as a 'key' to trigger the reaction. In terms of lower temps, then there is insufficient energy of activation to push the reaction forward.

What is the optimal temperature for invertase activity? Is this what you expected? Would invertase isolated from any two organisms (for example, yeast invertase vs. invertase from the small intestine of humans) show the same optimum temperature? Why or why not? Explain your answers. The optimal temperature for the invertase activity is 50 degree Celsius. Yes, this supports my hypothesis. Invertase for two organisms would show the same temperature optimum as the specific temperature for the invertase would not vary in different organisms because invertase regardless of source would have the same chemical structure. Explain why temperatures lower or higher than the optimum cause decreases in invertase activity. What is happening to the enzyme to produce these decreases in activity?   Invertase is an enzyme. Enzymes have very limited ranges of effective temperature. This is due to degradation of the chemical structure at higher temperatures. The enzyme may still work at lower temperature but may take longer. The reaction needs a specific amount of energy to proceed and that is where obtaining the lower optimum temperature comes in. Substrate would be binded to the enzyme as the result of higher temperature and this would led to the decrease in the activity.

Carefully examine the curve for VO vs. Temperature. Is the slope of the line on both sides of the curve the same or different? If the slope of the line to the left of maximum velocity is different from the slope of the line to the right of maximum velocity, explain why this is. What is responsible for these differences in enzyme kinetics?  

Series| Best Temp|
1| 50.0 °C|

As seen in the above graph, the left and the right of the line have different slopes. On the left, velocity gradually increased where as on the right it gradually decreased. This difference is due the binding of the active site of an enzyme by the substrate. As the substrate was binded on the enzyme’s active site due to high temperature, it altered the chemical structure of the enzyme which is basically the protein and therefore it resulted into the decrease in the activity of the reaction.

If you were to carry out these temperature experiments at a higher or lower [S], what effect would [S] have on the temperature optimum for invertase? How would you test this? If...
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