Enzyme Solution Concentrations example essay topic

Introduction In this experiment, we intended to investigate the effect of the concentration of catechol oxidase on the reaction rate of catechol to ortho-quinone. Living things, to increase the speed of chemical reactions, use enzymes. Enzymes are a type of protein. Because of the fact that enzymes are proteins, they have certain shapes. These shapes create areas in which the substrate, the chemical that is broken down by the enzyme, can fit in and be broken down.

The way that this reaction takes place is shown in the enzyme-substrate complex model. The model in question reads: Enzyme + Substrate (s) 'a Enzyme-Substrate Complex -'a Enzyme + Products From this model, it can be determined that if there is a way of measuring the amount of product produced that one can detect the reaction rate. In this experiment, Catechol was the substrate, and it was reacted with catechol oxidase to produce ortho-quinone. Catechol Oxidase, which is the enzyme that was used, was derived from potatoes. This experiment was destined to test what the effects of differing concentrations of catechol and catechol oxidase would be on the reaction rate of this reaction.

In order to determine the effect catechol oxidase has on the reaction rate of catechol to ortho-quinone, a spectrophotometer was used. A spectrophotometer, or spec 20, is used to get a measurement of the amount of light being absorbed. Because Ortho-quinone becomes a colored solution over time, measurements can be taken over time with the spec 20 to determine the reaction rate. In this experiment, it was predicted that the higher the concentration of catechol and enzyme, the faster the reaction rate would be. Materials and Methods In this experiment, the enzyme used was cath ecol oxidase. This enzyme was derived from a potato.

To get the enzyme, first, the potato had to be prepared. The potato was first cleansed and weighed. The potato was then cut into small cubes of about one-quarter of an inch and was blended with an equal mass of water until it was blended thoroughly. This suspension was then filtered through a material called cheesecloth, and the liquid was put through a centrifuge at 2000 r. p. m. for 5 minutes. The supernatant was poured out and the pellet was then thrown away.

The supernatant was kept on ice to keep it from going bad before the experiment was finished. Next, a serial solution was made using the enzyme from the potato. First, the 6 mL of the enzyme was taken and placed into a test tube and labeled full strength. Next, 3 other test tubes were filled with 3 mL of water.

Then 3 mL of the full strength enzyme solution from the first test tube was placed in the second tube, which created the half strength solution. From the half strength solution, 3 mL of solution was taken and then added into the 3rd test tube. This created the one-fourth strength solution. Finally, 3 mL of the solution from the one-fourth strength solution was taken and then added to the final test tube. This created the one-eighth solution. In the second experiment, this was taken one step further to make a one-sixteenth solution.

In the first experiment, substrate concentration was kept constant, but the serial dilutions of enzyme solution were used. 5 mL of buffered catechol was put into four different spec 20 tubes. Next, 1 mL of each enzyme solution concentrations were added to it's own spec 20 tube. The rate of change of light absorbance was measured using the spec 20. The change in light absorbance relates to the rate of reactions. The changes in light absorbance were taken for three minutes and an average was found for each concentration.

In the second experiment, enzyme concentration was constant, but the serial dilutions of substrate solution were used. 3 mL of water and 1 mL of potassium phosphate was added to five spec 20 tubes. Next, 1 mL of each differing substrate, catechol, concentrations were added to it's own spec 20 tubes. The changes in light absorbance were taken for three minutes and an average was found for each of the differing concentrations. Results The results gathered from the experiment indicated that as the amount of catechol oxidase increased, the reaction rate also increased (figure 1). When the full strength enzyme was placed into the first spec tube it was noticed that the production of ortho-quinone occurred rather quickly.

As the enzyme became more diluted, the production of ortho-quinone took more time to occur. The results also showed that the reaction rate increased as the concentration of 0.024 M catechol increased, but once the data reached one rate, the reaction rate leveled off (figure 2). As this experiment took place, it was noticed that the color change only occurred quickly after testing the first spec tube. As the experiment concluded, the reaction time began to reach a constant. Discussion The results of this experiment show that as the concentration of an enzyme increases, the rate of the reaction will also increase. The more of an enzyme present, the higher the possibility of substrate to enter an available enzyme's active site.

The results also show that as the substrate concentration increases the reaction rate will rise to a rate and then level off. When the rate of reaction levels off, the enzyme has become saturated and can not move any faster. According to the enzyme-substrate complex model, all of the active sites are currently filled with substrate and cannot accommodate any more. This is also known as the enzyme being saturated with substrate. The goals set before the experiment have been achieved because the effects of enzyme and substrate concentration on the reaction rate have been realized. The results of the experiment also proved my hypothesis correct.

It was hypothesized that the increase of enzyme concentration would increase the reaction rate. During the experiment no errors in procedure and calculations were noticed. I feel confident in the results that were gathered from the experiment. The results of this experiment could aid those performing other experiments involving enzymes. If the researcher would like the reaction to occur at a greater speed, more enzyme could be added.

Literature Cited 1) E bner, Kurt E. 1975. Subunit Enzymes: Biochemistry and Functions. Marcel Dekker, Inc. New York. 2) Raven and Johnson. 2002.

Biology. McGraw-Hill Companies, Inc. New York. 1238 pp 3) Schultz, D.L. 2002. Biology 155 General Biology I Laboratory Supplement. 79 pp.