ENZYME KINETICS
standard preparation , substrate concentration & temperature effect
1. Explain the importance of standard reference
2. What is the function of iodine solution?
3. Explain why starch turned blue when reacted with iodine?
4. Provide the relationship between substrate concentration and enzyme reaction.
5. What is Km?
6. What is Vmax?
7. Conclude the effect of temperature on the production using amylase.
- Standard reference is important especially during the experiment as a guide to control the results obtained. Such as in these experiments, the standard reference was used to compare the actual results obtained with the theoretical results. Besides, it is commonly used to determine the concentration of a substance. The data obtained was inserted in the graph and being compared to see any changes either its follow the standard graph or not. The data or parameter measured commonly is absorbance and we can find out the concentration of the product from the graph. The standard reference helps us to determine if our results are correct or not. It is also guide us in making the correct curve in a graph.
2. What is the function of iodine solution?
- The function of iodine solution is to detect and test the presence of starch in a solution. We could estimate the concentration of starch in a solution by observing the concentration of dark blue colour (iodine). The concentration of dark blue colour solution is higher when there are lot of starch presence while the concentration of dark blue colour solution decreases when the starch presence decreases.
3. Explain why starch turned blue when reacted with iodine?
- Starch turned blue when reacted with iodine because the starch is made up of amylose and amylopectin. Amylose is unbranched while amylopectin is branched and more complex than amylose. When iodine reacted with starch, the starch separated into amylose and amylopectin. Amylose formed coiled and will turn into dark blue colour solution. Amylose is a soluble component of starch.
4. Provide the relationship between substrate concentration and enzyme reaction.
- As the substrate concentration is low, the enzyme reaction is slightly increase because the active site of enzyme is empty and depends on the available substrates to bind.
- As the substrate concentration increases, the enzyme becomes saturated with substrate. The enzyme reaction depends on the enzyme reaction itself.
- Increases in substrate concentration will increasing the enzyme reaction velocity until it reaches a maximum velocity, Vmax.
- When the maximum velocity, Vmax had been reached, available enzyme will be converted into enzyme substrate complex.
- The rate of reaction also depends on the affinity of the enzyme to bind with the substrate.
5. What is Km?
- Km is the concentration of substrate which permits the enzyme to achieve ½ Vmax.
- Also called as Michaelis constant.
- An enzyme with a high Km has a low affinity for its substrate, and requires a greater concentration of substrate to achieve Vmax.
- Low Km showed that the enzyme requires only a small amount of substrate to become saturated. The Vmax is reached at low substrate concentrations.
6. What is Vmax?
- Maximum velocity, Vmax.
- Vmax also known as the rate of reaction when the enzyme is saturated with substrate.
- It is important to show the reaction of enzyme.
7. Conclude the effect of temperature on the production using amylase.
- Based on our experiments with temperature of 20 ͦC and 28 ͦC. The absorbance results obtained for 28 ͦC were higher than 20 ͦC. From the data of absorbance, we could determine the reaction rate of enzyme. As the values of absorbance were higher, the reaction rate of enzyme was higher and vice versa. Increase in temperature will increases the rate of enzyme-catalyzed reaction. If the temperature increase continuously, until one stage the enzyme will denatured. The kinetic energy of the enzyme increase when temperature increases, thus will increase the number of collisions of the enzyme and substrate per unit time. As a results, the rate of the reaction of an enzyme increases.