Enzymes Catalysts In Biochemical Reactions Biology Essay


Enzymes are resourceful accelerators for biochemical reactions, like all accelerators enzymes tend to rush up reactions. Enzymes use alternate reaction tract of lower activation energy. They take portion in the reaction, and as a consequence their able to supply surrogate tracts. Throughout the reaction enzymes remain unchanged because they can non see any lasting alterations. Enzymes merely have the ability to alter the rate of the overall reaction ; they ca n’t impact the reactions place of the equilibrium ( Rsc ) .

In most instances a chemical accelerator will catalyse any kind of reaction, enzymes differ in this kind. Enzymes tend to be specific, and this is due to the form of enzymes molecules ( Rsc ) .

Enzymes are made up of several proteins in a third construction ; these proteins tend to be ball-shaped. Many enzymes consist of a protein and a non-protein, called a cofactors and coenzymes. Cofactors are inorganic molecules that bind to enzymes to assist them work illustrations possibly be zinc/magnesium ions ( Zn2+ , Mn2+ ) , and coenzymes are organic molecules that bind to enzymes to assist them map. An illustration of one of the most of import coenzymes is nicotinamide adenine dinucleotide ( NAD+ ) , this substrate Acts of the Apostless as an negatron bearer in cellular respiration ( Nelson Biology 12 ) .

Enzymes consist of active sites, which are parts of the enzyme molecule that have the ideal form and functional groups to adhere to one of the reacting molecules. The responding molecule that binds to the enzyme is called the substrate. An enzyme-catalyzed reaction takes a different way than a reaction without accelerator. When the substrate binds to the enzyme a reaction intermediate is produced. This intermediate has lower activation energy than the reaction without the enzyme accelerator ( Rsc ) . There are two sorts of enzyme reactions, catabolic and anabolic. In a katabolic reaction the interactions between the substrate and enzyme causes emphasis and distorts the bonds in the substrate, leting bonds to interrupt. In an anabolic reaction the enzyme allows two substrates to hold proper orientation to let bonds to organize between them. As a consequence the activation energy is lowered in both the catabolic and anabolic reaction ( Nelson Biology 12 ) .

Catalase is a common enzyme found in most works and animate being cells that maps as an oxidative accelerator, it decomposes hydrogen peroxide into O and H2O. It ‘s construction is made of 4 chief polypeptide ironss, which can each be over 500 aminic acids long. Catalase optimal temperature can change depending on the species ; likewise the optimal pH besides varies from about 4-11. In worlds nevertheless the optimal pH for catalase tends to be impersonal. One molecule of Catalase can interrupt down 40 million molecules of H peroxide each 2nd ( Catalase ) . The overall reaction is:

2 H2O2 a†’ 2 H2O + O2

Many factors such as temperature, pH, suppression of enzyme activity, substrate and enzyme concentrations can act upon the affect the enzyme has on the reaction.

As the temperature rises, responding molecules gain more kinetic energy, as a consequence the opportunities of a successful hit addition and therefore the rate additions. There is a specific temperature when an enzyme ‘s catalytic activity is at its upper limit. This optimum temperature is normally around human organic structure temperature ( 37.5 oC ) for the enzymes in human cells ( Figure 1 ) . When the temperature increases past the optimum temperature the enzyme becomes agitated, it begins to denature and finally lose its overall affect on the reaction ( Nelson Biology 12 ) . This occurs because the addition in temperature achieves higher kinetic energy and as a consequence the intra- and intermolecular bonds are broken in the enzyme molecule ( Rsc ) .

Each enzyme works within a reasonably little scope of pH degrees. Similar to temperature there is a pH at which its activity is at its upper limit, the optimum pH ( Figure 2 ) . This is because alterations in pH can make and interrupt intra- and intermolecular bonds, altering the form of the enzyme and finally the rate at which it will respond.

The rate of an enzyme-catalyzed reaction depends on the concentrations of enzyme and substrate. As the concentration of either is increased the rate of reaction additions ( Figure 3 ) . When substrate concentrations are increased the overall reactions returns to increase up to a certain point, at this point the active sites have become saturated by the substrate and there are no farther important alterations in the rate of reaction ( Figure 4 ) ( Rsc ) .

Some substances cut down or even halt the activity of enzymes in biochemical reactions. They do this by barricading or falsifying active sites of enzymes. These substances are referred to as inhibitors. Inhibitors that occupy the active site and forestall a substrate molecule from adhering to the enzyme are said to be competitory, as they compete with the substrate for the active site. Inhibitors that attach to other parts of the enzyme molecule, possibly falsifying its form, are said to be non competitory ( Nelson Biology 12 ) .

Figure 1: Table 1Analysis

Sum of H2O2 ( milliliter )

Sum of Distilled Water ( milliliter )

Sum of pH Buffer ( milliliter )

pH Level

Vertical Distance Travelled by Filter Paper Towards Meniscus

Time taken by filter paper phonograph record to travel to meniscus ( s )

Upward speed of Filter Paper Disc ( cm/s )

10 milliliter

5 milliliter

7 ( Control )




10 milliliter

5 milliliter





10 milliliter

5 milliliter





10 milliliter

5 milliliter





Figure 2: Graph 1

Test Tube

Temperature ( A°C )

Distance ( centimeter )

Time ( s )

Rate of Reaction ( cm/s )


























Figure 3: Table 2As the pH increased from 2-7 so did the speed of the reaction ( refer to calculate 1: table 1 ) . The reaction had an optimum pH of 7, and as the pH increased after the speed of the reaction quickly decreased. Notice the speed for pH 12 is higher so the speed of pH 9 ( refer to calculate 2: graph 1 ) .

Figure 4: Graph 2 As the temperature increased from 10oC-30oC so did the rate of the reaction ( refer to calculate 3: table 2 ) . The reaction had an optimum temperature of 35oC, and as the temperature increased after the rate of the reaction began to quickly diminish ( mention to calculate 4: graph 2 ) .

Enzyme concentration

Distance ( centimeter )

Time ( s )

Rate of Change ( cm/s )

Other observations

100 % concentration

8 centimeter

3.02 s

2.65 cm/s

– bubbles appeared

80 % concentration

8 centimeter

5.06 s

1.58 cm/s

– fewer bubbles than old composing

60 % concentration

8 centimeter

6.28 s

1.27 cm/s

– fewer bubbles than old composing

40 % concentration

8 centimeter

7.5 s

1.07 cm/s

– fewer bubbles than old composing

Figure 5: Table 320 % concentration

8 centimeter

19.65 s

0.41 cm/s

– no bubbles appeared

Figure 6: Graph 3

Figure 7: Table 4

Figure 6: Graph 3Increasing the concentration of the enzyme catalase ( potato juice ) quickly increased enzyme activity ( refer to calculate 6: graph 3 ) .

Concentration of

H202 of Distilled Water


Time of catalase to go from the underside of the trial tubing to the top ( s )

Distance of underside of trial tubing to substrate ( centimeter )

Rate of alteration of the catalyzed reaction ( cm/s )

15 milliliter of H202

3 %













13 milliliter of H202 2.6 %













10 milliliter of H202 2 %













7.5 milliliter of H202 1.5 %













5 milliliter of H202 1 %













Figure 9: Table 5

Figure 8: Graph 4Increasing concentrations of the substrate slowly increased from 1 % to 2 % ( refer to calculate 8: table 4 ) , so as substrate concentrations increased more the rate of alteration became more rapid ( mention to calculate 9: graph 4 ) .

Experiment Number

Sum of Inhibitor ( Cu ( II ) sulfate ) ( beads )

Time taken by enzyme phonograph record to drift to exceed of trial tubing ( s )

Distance travelled by enzyme phonograph record to exceed of trial tubing ( centimeter )

Rate of Change of Enzyme Activity ( cm/s )


























Figure 10: Graph 5

As the sum of Cu ( II ) sulfate increases the overall reactions begins to decelerate down, and the rate of reaction lessenings ( refer to calculate 10: graph 5 ) .


Part One: Affects of pH Enzymes are really sensitive to alterations in pH, and important alterations in pH can impact enzymes in legion ways. The effects of pH on enzyme activity are due to alterations in the ionic province of the amino acid sedimentations of the enzyme and the substrate molecules. These fluctuations in charge will impact the binding of the enzyme and as a consequence, enzyme activity will increase or diminish. Over a tapering pH scope these effects will be reversible nevertheless high acid degrees frequently cause lasting denaturation of the enzyme ( Users.rcn ) . Before carry oning this experiment one can expect that pH degrees excessively high or excessively low would do the enzyme to denature and therefore it would no longer hold an affect on the overall reaction. In this experiment 5 pH degrees were used 2, 4, 7 ( control ) , 9, and 12. When the buffer solution affected the pH degrees of the H2O2 from 2 to 4 there was a little addition in enzyme activity ( from 0.47 m/s to 1.16 m/s ) . There was one control trial tubing incorporating H2O2 with a impersonal pH of 7. This trial tubing conducted the highest speed of 1.23 m/s. As a consequence the optimum pH for the H2O2 was at a impersonal pH of 7. When the pH degree of the H2O2 increased to 9 the speed seemed to diminish, which illustrated the loss of the consequence of the enzyme. However this tendency did non look to stay consistent because when the pH degree was increased to 12 the speed of the enzyme besides increased. As a consequence, it can be stated that enzymes work best in the part of impersonal pH degrees, and when pH degrees become excessively high or to low enzyme activity decreases therefore the hypothesis proved to be partially right.

Part Two: Affects of Temperature The temperature of the H2O2 can badly impact the overall result of a reaction. Like most chemical reactions, enzyme-catalyzed reactions besides increase in velocity with an addition in temperature. As the temperature of the enzyme increases past a critical point thermic agitation begins to interrupt the protein construction ensuing in the denaturation and loss of enzyme map ( Nelson Biology 12 ) . The hypothesis for this experiment was similar to that of pH, temperatures excessively high or excessively low would do denaturation of the enzyme and therefore it would no longer hold an affect on the overall reaction. In this experiment 5 different temperatures were used 10oC, 21oC, 35oC ( control ) , 50oC, and 80oC. When the temperature was decreased to 10oC the rate of the reaction was at it lowest of 1.38 m/s. At 21oC the rate somewhat increased to 1.66 m/s. Therefore there is a tendency of lower temperatures doing the enzyme to lose its overall affect. There was one control trial tubing incorporating H2O2 that was at room temperature which was 35oC. This trial tubing conducted the highest rate of reactions of 2.68 m/s. As a consequence the control trial tubing achieved the optimum temperature. When the temperature of the H2O2 began to increase from 50oC to 80oC there was a tendency of the enzyme losing its affect, and holding an overall lower rate of reaction. As the temperature increased before the optimum temperature the rate of the reaction increased, and when the temperature continued to increase past the optimum point there was a rapid lessening in the rate of the reaction therefore it is apparent the hypothesis was right.

Part Three: Affects of Changes in Concentrations The rates of enzyme-catalyzed reactions badly depend on the concentrations of enzymes and substrates. If one individual is forcing a auto it probably that auto will take longer to acquire to and stop point, nevertheless if 10 people are forcing that same auto it will evidently acquire to the terminal point a batch quicker. It is the same with enzyme and substrate concentrations, the higher the concentrations the faster the reaction works. As the enzyme concentration additions so does the figure of enzyme molecules, therefore more substrate molecules can be acted upon at the same clip which means they breakdown a batch faster. As the substrate concentrations addition, the reaction besides proceeds to increase nevertheless with high degrees of substrate concentrations the active sites become concentrated and the enzyme no longer has an consequence of the reaction ( Worthington-biochem ) . The hypothesis for this experiment was simple, as enzyme and substrate concentrations increase so will the velocity of the reactions. When altering the substrate concentrations, the five H2O2 concentrations where 3 % ( control ) , 2.6 % , 2 % , 1.5 % , and 1 % . The chief tendency in this experiment was the higher the concentration of the substrate the higher the rate of alteration. There was a important and rapid addition in the rate of alteration from concentrations of 2 % to 3 % . When altering the enzyme concentrations, the five murphy juice concentrations where 20 % , 40 % , 60 % , 80 % , and 100 % . Changing the concentration of the enzyme had a similar affect to when the substrate concentrations were changed. The more concentrated the enzyme was the higher the rate of the reaction. The rate of the reaction quickly increased from 20 % to 40 % , nevertheless it became a spot changeless from 40 % to 80 % , and from approximately 80 % to 100 % it began to quickly increase once more. As a consequence, it is apparent the hypothesis was right as the concentrations increased so did the reactions.

Partially Four: Consequence of the Inhibitors Inhibitors are used to barricade active sites of enzymes. They are substances used to decelerate down, or in some instances stop contact action. Inhibitors either compete with a substance for the enzymes active site ( competitory ) , or they bind to another site on the enzyme altering its form ( non-competitive ) ( Nelson Biology 12 ) . Before carry oning this experiment one can expect the more sum of inhibitor present the slower the reactions will continue. In this experiment Cu ( II ) sulfate was used as the inhibitor. In the five tests 0, 1, 5, 10, and 15 beads of the Cu ( II ) sulfate were used. The obvious tendency was the more inhibitor the lower the rate of reaction. Therefore, the hypothesis was right.

Beginnings of Mistake

Error # 1: Consistency of Filter Paper

When carry oning each single experiment for many groups it seemed the most hard undertaking was acquiring the filter paper to get at the underside of the trial tubing. When the filter paper was placed in the trial tubing it would travel about half manner down the trial tubing, nevertheless because the reaction catalyzed rapidly the filter paper would get down to lift and go back up to the top of the H peroxide liquid. As a consequence you would hold to execute the experiment once more, with a new catalyzed filter paper. This became a beginning of mistake because it made it hard to roll up consistent informations. For every trial tubing, and test the filter paper did non make the underside of the trial tubing at the exact same clip. In some instances it would make the underside without trouble, and in other state of affairss it became a changeless battle to force it down the trial tubing. During certain tests the experiment had to be performed once more and the H peroxide had already lost its affect from the old catalyzed reaction. As a consequence, it is apparent that the consistence and rate at which the filter paper travelled down the trial tubing is a important beginning of mistake. To better this beginning of mistake, heavier and more lasting filter paper should be used. One can buy “ wet strength ” filter paper which will do its manner down the trial tubing on its ain without any human force.

Error # 2: Accuracy of Inhibitor

During this experiment it became hard to acquire precisely 15 milliliter of H peroxide after the inhibitor has been added. Copper ( II ) Sulphate is a badly little dissolver so when added to the H peroxide one can non command the sum of liquid nowadays. This occurs because before adding the Cu ( II ) sulfate it is unsure how much H peroxide needs to be reduced in order to hold precisely 15 milliliter. This creates a beginning of mistake because now the information collected is inconsistent because of the different volumes of H peroxide. To forestall this beginning of mistake one can utilize a different inhibitor that will fade out in the H peroxide and non alter its volume.

Error # 3: Catalase in Potatoes

During the experiment murphy juice was invariably being pumped and used as the enzyme to catalyse the reactions. However it was non considered that each murphy is harvested in a different manner and one murphy may hold several foods, while the other may be wholly dead. This consequences in the difference of concentrations of catalase that was taken from each particular murphy. Once once more this beginning of mistake causes a incompatibility in the aggregation of informations because one can non be certain they used the same murphy, that pumped a changeless concentration of catalase throughout the whole experiment. For the intent of this experiment if merely one murphy was land and made into murphy juice so catalase concentrations would be consistent and it would extinguish this beginning of mistake.

Following Stairss

A similar experiment that could be performed is Saturation Points of Substrate Concentrations. In the current lab impregnation was non tested when altering about substrate concentrations. One can prove the sum of substrate it would take to saturate the active site on the enzyme, and continue to measure how much more of the enzyme concentration is needed to unsaturate and disassociate the substrates from the active site of the enzyme.

Another experiment that could be performed is Affects on Assorted Enzymes. Alternatively of merely detecting the affects of alteration of pH, temperature, concentrations, and inhibitors on Catalase it can be tested on other enzymes. For illustration Cellulase, Lactase, and Pepsin.