This may result in a change in the bonds and so the tertiary structure may break down. The active site will be disrupted and the enzyme will be denatured.
Enzyme Concentration - at low enzyme concentration there is great competition for the active sites and the rate of reaction is low. As the enzyme concentration increases, there are more active sites and the reaction can proceed at a faster rate.
Eventually, increasing the enzyme concentration beyond a certain point has no effect because the substrate concentration becomes the limiting factor.
Substrate Concentration - at a low substrate concentration there are many active sites that are not occupied. This means that the reaction rate is low.
When more substrate molecules are added, more enzyme-substrate complexes can be formed. As there are more active sites, and the rate of reaction increases.
Eventually, increasing the substrate concentration yet further will have no effect. The active sites will be saturated so no more enzyme-substrate complexes can be formed.
FAIR TEST: To obtain accurate and reliable results, i must only change one factor during each experiment, and keeping all other factors, listed above, constant throughout each experiment.
Since i am testing the effect of enzyme concentration, the only variable in the experiment should be enzyme concentration and nothing else.
APPARATUS:
-funnel
-2 pipettes
-2 stop clocks
-test tubes
-spatula
-2x150cm3 beaker
-75g of 2.0% gelatine solution
-pH 2.8 buffer
-trypsin solution (5%)
-glassware for diluting enzyme
-milk powder solution
-test tube holder
-waterproof pen
-ruler
-standard acidific trypsin solution 19%
-5cm3 pipettes
50cm3 beaker
-glassware for dilution of the enzyme
METHOD: 5cm3 protein solution was pipetted into a test tube and mixed thoroughly.
The stop clock was then immediately started and the time taken for the protein solution to clear was recorded. This was repeated two more times for accuracy.
These exact procedures were repeated with different enzyme concentrations, ensuring that the conditions are unchanged.
The different enzyme concentrations were used:
1% - 5cm3 enzyme solution STRONGER
0.5% - 2.5cm3 and 2.5cm3 water
0.25% - 1.25cm3 enzyme and 3.75cm3 water
0.10% - 0.5cm3 enzyme and 4.5cm3 water WEAKER
RESULTS:
CONCLUSION: The results i have obtained have shown that a decrease in concentration of enzymes results in an increase in the timetaken for the solution to clear. In other words, as the concentration of protease decreases, the amount of active where the reaction takes place also decrease, therefore causing a lower rate of reaction - the time taken for the trypsin milk protein to be broken down is slower.
The results have also shown my prediction to be correct. In my prediction, i stated that a higher enzyme concentration results in a faster rate of reaction - that the protein solution, the trypsin casein, would turn clear much quicker when the enzyme protease is more concentrated.
My results show that the protease at a concentration of 1% (the highest concentration used in the experiment) turned the trypsin casein solution clear in the space of 3.10 minutes. Whereas, when the protease enzyme was not at a concentration of 0.1% (the lowest concentration used), the amount of time it had taken for the trypsin solution to clear was 14.30 minutes.
In conclusion, when there are higher enzyme concentrations, there are more enzyme molecules, which means that there is an increase in active sites available to catalyse the reaction. Higher activity occurs at higher concentrations.
EVALUATION: There were many factors, which could have affected the results ofmy experiment. The main source of error was judging if the solution had turned clear. It was very difficult to do this, and it was impossible to judge whether the solution had purely turned clear. If the protease-trypsin solution had not turned fully clear, then the experiment is not complete.
A solution to this would be to use a calorimeter. Here, the light emitted by the solution comes to the same frequency as on the calorimeter, and this will increase accuracy of results. This also removes the need of judgement by the eyes.
Another major factor, which could have affected the results of the experiment was the mixing together of the protease and trypsin solutions in the test tubes. Here, if the solutions are not fully mixed, then this would be unfair as some areas would be more concentrated than others, causing inaccurate results.
To solve this, a preperation of a standard solution may be done. Here, a flask could be used to mix the two solutions together. When adding the two solutions together, the flask would be inverted a reasonable amount of times, approximately six. The amount of times it is inverted must stay constant throughout each experiment to avoid unfairness. Inverting must be done slowly to allow time of proper mixing between the two solutions, also so the solution can reach both ends of the flask each time inverting. Carrying this process ut can result in a much better chance of a fully mixed standard solution.
Other factors in which error could have occured are inaccurate measuring - here, i can only read measurements accurately to the nearest millametre, when to start timing - here, starting the clock must be done immediately after mixing the solutions, and some solutions may have taken longer to mix, and the clock therefore being started at different times during each experiment, and temperature of the surroundings - temperature can affect the rate of reaction. If the temperature of the surroundings changes, this can cause a temperature change in the solution. As stated earlier, enzymes work best at an optimum temperature. Below this, the rate of reaction increases, and above this, the rate of reaction decreases, both causing inaccurate results.
