• Subject Code : BIOL2260
• University :
• Subject Name : Biology

## Biological Chemistry

Results and Discussion:

Table x. table caption

 Temperature 4 °C 21 °C 30 °C 37 °C 90 °C Absorbance at zero min 1.06 1.164 1.155 1.070 1.026 Absorbance after 10 min of incubation 0.99 0.537 0.131 0.029 0.855 A0min – A10min Enzyme activity in 10 min (µmoles) Enzyme activity (µmoles pyruvate/min)

CALCULATIONS:

Pointers for discussion: What was the best temperature for enzyme activity.

The best temperature for the enzyme activity was 37oC.

When we determined the difference in absorbance rates at zero and ten minutes, it was greater for the temperature 37oC. An enzyme works efficiently at a certain temperature called the best or optimum temperature. The temperature at which the enzyme has the maximum speed of activity is called optimum temperature. Every enzyme has a particular value of optimum temperature at which it can show its maximum activity. As shows LDH at 37oC in this situation. The value was as follows:

A0minA10min = 1.070 – 0.029 = 1.041

Why do you think this is the best temperature?

A temperature is the best temperature for an enzyme activity if it has maximum activity at that temperature. An enzyme works efficiently at a certain temperature called the best or optimum temperature. The temperature at which the enzyme has the maximum speed of activity is called optimum temperature. Every enzyme has a particular value of optimum temperature at which it can show its maximum activity. As shows LDH at 37oC in this situation. (Dettbarn & Ramesh, 2006)

When we determined the difference in absorbance rates at zero and ten minutes, it was greater for the temperature 37oC. The value was as follows:

A0minA10min = 1.070 – 0.029 = 1.041

What happens to the enzyme at other temperatures, specifically at high and low temperatures?

An enzyme works efficiently at a certain temperature called the best or optimum temperature. The temperature at which the enzyme has the maximum speed of activity is called optimum temperature. Every enzyme has a particular value of optimum temperature at which it can show its maximum activity. As shows LDH at 37oC in this situation. While we change the temperature from the optimum temperature, there is a decrease or increase in the rate of the reaction. If the temperature is decreased from the optimum temperature, the activity of enzyme falls down. In the same way, if the temperature is increased form the optimum temperature, the activity decreases again. The factors for the change in activity are different for low and high temperatures. (Makert, 1984)

Table x. table caption

 pH 3 5 6 7.4 8 9 Absorbance at zero min 0.770 0.772 0.778 0.764 0.715 0.721 Absorbance at one min 0.656 0.580 0.364 0.156 0.381 0.536 A0min – A1min Enzyme activity (µmoles pyruvate/min)

CALCULATIONS:

What was the best pH for enzyme activity?

The best pH for the enzyme activity was 7.4.

When we determined the difference in absorbance at zero minute and at one minute, it was maximum for the pH value 7.4. The absorbance difference at this pH value was as follows:

A0minA1min = 0.764 – 0.156 = 0.608

Why do you think this is the best pH?

A pH value is best for an enzyme activity if it has maximum activity at that pH value.

When we determined the difference in absorbance at zero minute and at one minute, it was maximum for the pH value 7.4. The absorbance difference at this pH value was as follows:

A0minA1min = 0.764 – 0.156 = 0.608

Most proteins have a relatively stable conformation at pH 6 or pH 8. Assuming that LDH has a stable conformation in this pH range, explain what factors you think might contribute to changes (if any) in the activity of the enzyme at the different pH’s tested?

Every enzyme has a certain pH value at which it works efficiently. Above or below this pH value, the amino acids in the active site of the enzyme start ionizing. More we change the value of pH from the optimum pH, the more ionization of active site occurs. The ionization of the active site changes the structure of the amino acids. In return, it is difficult for the substrate to bind with the active site. An enzyme is specialized for one type of substrate. If the structure of the active site is changed, it will be unable to identify its substrate, and hence the reaction will not proceed. It will cause the rate of reaction to decrease. Violent changes in the pH values cause the destruction of the globular structure of an enzyme, in which case the enzyme is unable to work. The pH of an enzyme is the most unique and sensitive factor for its activity. The minor changes in pH can even show the marked difference in the activity of the enzyme. The reason is that the enzymes can work efficiently and properly in the particular nature of the medium. The change in the pH causes the nature of the medium to change which will ultimately change the activity of the enzyme. (Farhana & Lappin, 2020)

From your studies where you determined rate of change in absorbance every 30 seconds (pH experiments), is the rate of reaction linear over the 5-minute period? If not, why do you think the rates are not linear over this period of time?

The rate of the reaction in the 5-minute period was linear. As the temperature was increased, the rate of the reaction was also increased. The rate of the reaction was accelerated linearly with the increase in temperature. However, the rate of reaction went down with the increase of temperature after the optimum temperature. The reason is that an enzyme can work at maximum speed at its optimum temperature, that was 37oC in this case. The reactions in which the rate of the reaction increases linearly with the change in the temperature are said to be linear. If the there is no linear relationship between the rate of reaction and the change in the temperature, then it would be a non linear reation. However, in this case, the rate of reaction is linear.

Why do we use initial velocity to determine enzyme activity?

The formation of the products of a reaction in a linear way in the initial state is called the initial velocity of a reaction. It is important to know the initial velocity of a reaction. The reason is that it tells us the information about the fate of the reaction as well as the prediction of the amount of substrate that can be utilized in the reaction. Initial velocity of a reaction is a very important characteristic that can predict the amount of the product formed in the reaction or the amount of the reactant that is utilized in the reaction. The initial velocity of a reaction for an enzymatic reaction is directly related with the concentration of the substrate of that enzyme. It increases in value with the increase in the concentration of the substrate. However, it is not further affected by the substrate after a certain concentration.

## References for Lactate Dehydrogenase Enzyme Activity

Dettbarn & Ramesh, 2006. Lactate dehyderogenase enzyme conversion, s.l.: Clinical Biochemistry of Domestic Animals.

Farhana, A. & Lappin, S., 2020. Biochemisty of lactate dehydrogenase, s.l.: s.n.

Makert, C., 1984. Biochemisry and function of lactate dehydrogenase, s.l.: s.n.

Remember, at the center of any academic work, lies clarity and evidence. Should you need further assistance, do look up to our Biology Assignment Help

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