The Effect of Different Substrate Concentrations on the Rate of Reaction

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

Research Question: What is the effect of substrate concentration (as measured in % concentration) on the rate of enzyme activity (as calculated by the dividing the measured distance in cm, +/- 0.1 cm, travelled by a substance in a manometer by the time in seconds, +/- 0.5 seconds)?

The purpose of this experiment is to see how the enzyme peroxidase performs under different conditions. An enzyme is a protein molecule that is a biological catalyst. A catalyst is a substance that speeds up a chemical reaction, while also lowering the activation energy of a reaction. The activation energy of a reaction is the initial amount of energy that is necessary to bring reactants together with the proper amount of energy and placement so that products can be formed. Enzymes have a unique 3-D shape, which enables it to stabilize a temporary association between substrates (the reactant molecules that binds to the active site of an enzyme and undergoes chemical modification).

What effect does pH have on the enzyme catalase and its ability to decompose H2O2? Catalase helps living organisms break down hydrogen peroxide (H2O2) faster due to the toxicity. Hydrogen peroxide tends to be broken down into water and oxygen by catalase.

First off, the rate of the reaction at the pH of 7 was the highest, and this is because it was in its optimal environment (Piper 1965). If an enzyme is located in its optimal environment, or one that it prefers the most, it will be more active in that environment versus if the enzyme was located in a different environment. On the other hand, the rate of reaction for the pH of 4 and 10 was 0, or no reaction took place. The reason why this occurred is that because of the extreme pH ranges, the enzyme deactivated and can no longer complete this reaction successfully (Piper 1965). If this is examined further, it can be found that the enzyme actually denatures, or loses the shape it needs to function properly. Also, along with the preferred pH determining the activity of enzymes, the type of enzyme also determines which pH it has the most activity at. Peroxidase is an enzyme that comes from the root vegetable Brassica rapa subsp. rapa, and Peroxidase is known to affect plant growth (Kao 2001). Even though growth is not tested, it still explains that Peroxidase comes from a plant and affects plants, and plants require a neutral pH to survive. This explains why the pH of 7 has the highest rate of reaction, because the pH of 7 is neutral. It also explains the reverse, that the reaction rate at the pH of 4 and 10 is nothing, because those pH’s are

High pH changes can course denaturation of the enzyme. At low substrate concentration, rate of reaction increases with increasing substrate concentration. The continued increase in substrate concentration, leads to the saturation of the enzyme by the substrate. Addition of further substrate will affect the rate of reactions. A typical graph of rate of reaction and substrate concentration gives a hyperbolic shape indicated by the figure 1 below.

So a slight change of pH would drop the reaction rate because the enzyme’s shape is disrupted, thus the enzyme’s active site would change. But the change in the values of pH would not denature an enzyme. The bonds would be interfered because of pH change, however they can reform when the pH returns to the optimum point. The enzyme’s denaturisation only happens if there is an extreme alteration of pH (the enzyme at too low or high

Introduction Enzymes are found in humans, animals and plants. An enzyme is a protein that acts as a catalyst, which brings out a biochemical reaction. Biochemical reactions are important in humans because they help with many important functions such as digestion and the breaking down of waste in the body. Catalase is an enzyme found in almost all living organisms that are exposed daily to oxygen (such as fruits, vegetables and animals). To determine how Catalase reacts with hydrogen peroxide (a compound also found in the human body) under two different conditions is the focus of the following experiment called the, “Enzyme Experiment.”

Enzymes play a critical role in metabolic processes by speeding up chemical reactions. Enzymes lower energy barriers by acting as a catalyst for a reaction. An example is hydrolysis that occurs in glucose. Without enzymes glucose will still hydrolyze, but at a slow rate. With the right enzyme hydrolysis will occur even more rapidly than before. Enzymes work by having a substrates enter their active site. Induce fit (the substrates forms weak bonds with the enzyme causing the enzymes shape to enfold the substrate) than occurs to the enzyme. It must be kept in mind however, that the enzymes only work on specific substrates and not all of them also known as enzyme specificity.

Specific enzymes made up of proteins are used in biology to speed up a chemical reaction of any kind. Since a spontaneous chemical reaction can occur without help from any outside energy it could potentially prolong the reaction to where it becomes almost unnoticeable since it can take years for it to happen. For this reason, enzymes take action as a catalyst that speed up the reaction rate without completely being absorbed (Campbell et al., 2010). Enzymes are a form of regulation that allow for a through pathway in chemical reactions. It is able to perform as a catalyst by lowering the activation energy which is the energy required to drive the reactant to the top of the energy barrier allowing the downhill part to begin. An

Our group performed the test of decreasing the substrate concentration in the catalyzed reaction decomposing hydrogen peroxide into water and oxygen gas. For our baseline, we set up a reaction using 10 ml 3% hydrogen peroxide (the substrate) and 1 ml yeast (the catalyst). We then calculated the reaction rate to be 0.09375 ml/sec of oxygen produced. This reading is based off of the initial part of the curve, before the plateau. Once the rate decreases in the data too much peroxide has been used up to retain a steady reaction rate, so it is not reliable data for use in calculating the true rate. At this point we hypothesized that a lower rate would be observed for lesser concentration of substrate because there would be fewer molecules and

The result of our data isn’t accurate, and has flaws in terms of timing and accuracy. Next time, before I time the enzyme catalase for 2 minutes when I insert and get the enzyme catalase out, I will time 15 seconds, instead timing at random and inconsistently. Also, our experiment only used 4 different temperatures of the hydroperoxide, which consists the idea that next time we can increase the sample sizes by using more temperatures. Next time, we should find out the temperature when the enzyme catalase lose its its shape. Since the enzyme lost its shape until warm water that was 43° and lost its shape at hot water of 95.8° we can have more temperature between both the warm and the hot water.

The enzymes when placed in hydrogen peroxide (H2O2) make an end product of oxygen and water. Many outside factors make this experiment vary from one group to another. The temperature of the enzymes plays a critical part on how the enzymes react in a situation where they have to catalase something. The concentration of hydrogen peroxide does not vary the outcome. The thing that varies the outcome most is the type of enzyme and the temperature at which they are at. If an enzyme is too

In temperature, when it increases, it is expected that the activity of Catalase will also increase up to a certain temperature. After a certain degree, it is expected that the activity of Catalase will slow down and eventually come to stop. Similarly, it is expected that more concentration of substrates will lead to higher activity of Catalase up to a certain concentration level. Past that certain level, the productivity of the enzyme will stop. On the other hand, for pH and salt concentration level, it is expected that too low or too high in either variable will lead to

In this specific experiment, the pH of the environment in which the reaction took place was altered in order to observe how the rate of the enzyme catalase’s activity would be affected. Like most other enzymes, catalase performs optimally at a pH of 7. For the purposes of this experiment, the varying pH levels were assigned as the independent variable and the rate of enzymatic activity was the dependent variable. From a molecular standpoint, pH levels can change the shape of an enzyme, causing the active site’s shape to change and not allowing the substrate to fit in correctly. The pH levels may also change properties of the substrate, in which case it may not bind properly and result in an ineffective catalyzation (Nishiura). In this way, varying the pHs allows for the rate of enzymatic activity to be observed since there will be an optimal pH at which the enzyme and substrate’s shape and integral properties are retained. Any deviation from this pH will