Enzyme Catalyst Lab

Enzyme Catalyzed Reactions (Including Base Line)

 

Purpose

 

In this first part of the lab, we will determine how excessive pH effects the productivity of an enzyme. Some enzymes work well at higher pH's, while others are more adapted to lower ones. Regardless, every enzyme has an optimum and preferred pH range to work in. By moving an enzyme outside its comfort zone, we will observe the result by noting the change in the rate of the metabolic reactions taking place at the same time. Changing the pH will denature the protein

Introduction

This lab will focus on enzymes and their role in accelerating metabolic reactions by reducing the amount of activation energy required to start a given reaction. Enzymes are simply proteins produced by cells and are catalysts. It is important to understand that catalysts will always assist the reaction without being used up in the process. Therefore, enzymes within our body will continue to operate efficiently unless they encounter an adverse conditions, such as an acidic solution or extreme temperatures. Finally, each type of enzyme is specific to a particular substrate, like sucrase working primarily with the substrate sucrose. In order for our body to break down a myriad of food items, we need a large quantity enzymes to bind with as many substrate molecules as possible so that reactions can be fast and effective.

 

 

Methods

 

                       

For the Base Line Lab we added 10 mL of H2O2, then 1mL of water, and 10mL of H2SO4. Lastly, we added KMnO4 into the 5 mL solutions which we added little by little and mixed in between the drops until the solution turned a bright pink

        

Similar to be base line lab, we added 10 mL and (instead of water) we added 1 mL of catalase extract. At different time intervals, while mixing at the same time , we added 10 mL of H2SO4 into the beaker.

 

Data & Graphs

 

This table shows the results of our enzymatic reaction. As the time increased, the amount of KMno4 decreased while the amount of h2o2 increased. 

 

This graph is taken from part e of the data table. As the independent variable, time, is increased, the amount of H2O2 is also used up. This graph shows an increase of hydrogen peroxide used up from 10 to 30 seconds, then a dramatic decrease, and then a more stable increase until 180 seconds. 

 

Discussion

 

For the most part, our results in this lab were fairly close to what is to be expected, with only one major outlier due to experimental error. The summary of our results can be explained by this sentence: The longer the hydrogen peroxide is exposed to the enzyme catalase, the more of it is broken down to water and oxygen gas. The base line titration had the highest amount of KMnO4 used because it had the highest amount of hydrogen peroxide, as almost none of it was decomposed (the table shows the amount of hydrogen peroxide used, not the amount of KMnO4 consumed).  As soon as we added the sulfuric acid which significantly lowered the pH, the enzymes (as a globular protein) were denatured and the reaction slowed down significantly. From this conclusion, it can be hypothesized that changing other factors, such as temperature, would also promote or inhibit the reaction rate, because proteins can denature when exposed to temperature extremes. By looking at the graph, it is easy to tell there is a serious problem with the 60 second reaction. It does not follow the generally increasing slope of all the other points. One possible explanation would be that water was accidently mixed with the hydrogen peroxide as they are both clear liquids. This would significantly dilute the hydrogen peroxide in the solution to a point where KMn04 titration would take place rapidly and with little KMnO4. Overall however, the longer the reaction rate the greater the amount of hydrogen peroxide converted and the less amount of titrate used.

 

Conclusion

This lab shows how enzyme catalase increase the rate at which h202, hydrogen peroxide, decomposes.When enzyme catalase is added to h202, the catalase is denatured and oxygen is released. Enzyme catalyzed reactions  are affected by the environmental factors and changes such as temperature, pH levels, substrate concentrations, and enzyme concentrations.When we added sulfuric acid, the catalase wasn’t able to break down the hydrogen peroxide due to the change in environment, the ph change, which denatured the enzyme.

 

References

 

http://www.rcsb.org/pdb/101/motm.do?momID=57

http://elmhurst.edu/~chm/vchembook/568denaturation.html

 

 

Uncatalyzed Reactions

 

Purpose

 

Lowering the activation energy of a reaction will reduce the change in free energy when the reaction takes place, and allow the transformation of reactants into products to occur faster and more often. To see just how essential enzymes are to living organisms, we will note what happens when a reaction takes place without assistance from enzymes.

 

Introduction

 

Reactions can take place without enzymes-it just takes a lot more time and energy to get the reaction going. Hydrogen peroxide naturally breaks down into oxygen gas and water over time, as the reaction is spontaneous. The change in free energy is negative. HAVE KENNY ADD MORE TO THIS

 

Methods

 

 

This picture above shows the bubbling of H2O2 when catalase was added. This bubbling represents the O2 gas being released while the H2O2 

 

 

 

Data & Graphs

 

 

 

 

 

Discussion

The results of this lab indicate that the breakdown of hydrogen peroxide to water and oxygen will take place even without a catalyzer. What this proves is that the breakdown of hydrogen peroxide is spontaneous: the reaction releases energy, or is exergonic. In this case, given enough time, hydrogen peroxide will decompose on its own. The activation energy for this reaction, which was significantly reduced by adding catalase, is overcome in this instance by some other means. It is quite possible that the activation energy for this lab came from the atmosphere, as hydrogen peroxide does not decompose this quickly when placed in a sealed container. Nonetheless, this experiment showed that spontaneous reactions can and do occur even without a catalyst.

 

Conclusion

 

 

 

References

http://infohost.nmt.edu/~jaltig/HydrogenPeroxide.pdf