ENZYME REFLECTION
Explain the importance of standard reference
Standard references is used to find the values of concentration based on the value of absorbances. This is because the standard references used for this enzyme kinetic experiment are constantly based on the type of solution, means it is a standard solution. The factors considered to assaying the enzyme are pH, temperature, substrate concentration and ionic strength. However, for this experiment we just took 2 factors or called manipulated variables which are temperature and substrate concentration.
What is the function of iodine solution?
Iodine solution is functioning in detecting the presence of starch. If the starch are presence, the yellow colour of the iodine solution will turn into blue-black colour. If we use the iodine, we will know either the enzyme has break down all the starch or not.
Explain why starch turned blue when reacted with iodine?
Plant store glucose as the polysaccharide starch. Starch can be separated into two fractions which are amylose and amylopectin. This amylose consist of glucose molecules and form a spiral much like a coiled spring. The iodine will adhere the beta glucose in the starch because of their solubility. The starch will push the iodine into a line in the middle of the amylose coils and creates a transfer of charge between the iodine and starch. This will causing the changes in the arrangement of electrons and energy level spacings. The new spacing absorb visible light differently and create the deep blue colour.
Provide the relationship between substrate concentration and enzyme reaction.
The substrate will bind to the active site of enzyme to form enzyme-substrate complex. Then the enzyme-substrate complex will be splitted to form new product and free enzyme. From the experiment done, when the substrate concentration increase, the rate of enzyme reaction increase. However, when the rate of enzyme reaction at the optimum point, increasing in the substrate concentration will no more causing the rate of enzyme reaction increase. This can be conclude that all the available enzyme is already bind with the substrate to form enzyme-substrate complex.
What is Km?
Km is enzyme kinetic. Based on the graph 1/v against 1/[S] we plot, This Km can be calculated by using the equation. When the Km is larger, the affinity of the substrate for the enzyme is lower. Larger Km means that the substrate concentration must be higher for the enzyme to be half saturated. Lower Km means the substrate concentration must be lower for the enzyme to be half saturated.
What is Vmax?
Vmax is velocity maximum. Vmax is the rate of enzyme reaction when it was binded with the substrate at the maximum rate. Vmax is essentially a measure of how fast the enzyme can work when it is completely saturated with the substrate. This Vmax can be obtained from the graph and the equation. Larger Vmax means that the enzyme can bind with more substrate to form new product per unit of time and causing the rate of enzyme reaction increase. Lower Vmax means that the enzyme bind with less substrate to form new product per unit of time and causing the rate of enzyme reaction decrease.
Conclude the effect of temperature on the production using amylase.
When the temperature increase, the rate of enzyme reaction increase, the product form also increase. Variation in temperature although it is a small changes for 1 or 2 degree celcius, it can change the rate of enzyme reaction by 10 to 20 per cent. However, after reaching the maximum point, the rate of enzyme reaction will decreased. This is because at high temperature the enzyme will be denatured. We have used 20, 28, 35 and 40 degree celcius for this enzyme kinetic experiment.
Share your learning experience here.
Tell about your best and worst experiences
My best experiences is when I able to handle the temperature effect on enzyme rate by myself. I learned how to ensure the cold solution in test tube turn back into room temperature in short period without need for waiting. I also learned that the standard references are very importance to determine the value of concentrations. My worst experiment is when at first I still blur what I need to do with this experiment because I am not well prepared. But, I seek help from the other friends to explain my part and what I need to do. And the result is fabulous and I am happy handling many apparatus that I never use before.