1. For the reaction Substrate --> Product, the addition of an active enzymatic c

ID: 526747 • Letter: 1

Question

1. For the reaction Substrate --> Product, the addition of an active enzymatic cataylst would.... (put an X in the correct column. The first row has been done for you)

Would your answers be different for a non-enzymatic catalyst?

Yes

2. In the experiments that went into generating your calibration plot data, a H2O2 solution that is 0.003% by mass was used. What is the molarity of this solution? (Note: Mass Percent = Mass of solute/Mass of Solution * 100)

3. For the experiment conducted to generate the data for your calibration plot, 9.0 mL of 0.1 M phosphate buffer was combined with 0.2 mL of 62 Unit/mL horseradish peroxidase, 0.3 mL of each indicator, and varying amounts of 0.003% H2O2. If a total of 0.2 mL of H2O2 was added to the mixture, what is the final [H2O2] in units of moles H2O2/L solution?

4. Since horseradish peroxidase is in excess, each H2O2 molecule formed from the first enzymatic sugar oxidation reaction will be reduced by horseradish peroxidase to form one H2O molecule and one oxidized indicator molecule. The electrons for this reduction come from the indicator molecule, which becomes colored upon oxidation.
a.) What does this mean about the relationship between the concentration of H2O2 and the concentration of the indicator?
b.) Since we know from Beer's Law that the concentration of the colored species is directly proportional to the measured absorbance at a given wavelength, what does this mean about the relationship between absorbance and concentration of H2O2? In other words, more H2O2 means what about the absorption?

5. In the lab, you will generate rate plots under different conditions (pH, temperature, sugar identity) as part of this experiment, where you will have to plot product concentration against reaction time. Write the equation (with as few variables as possible!) that you will use to determine concentration of oxidized sugar. Include any calculations or graphs that you may have made to arrive at that form of the equation.

6. How will you use your plot of indicator concentration against time to determine the reaction rate for the enzyme-assisted oxidation of sugar?

Increase Decrease Not Change No way to tell Rate of the forward reaction X Rate of the backward reaction Activation Energy Delta H of the overall reaction Delta S of the overall reaction Delta G of the overall reaction

Explanation / Answer

Enzymes are biocatalysts that accelerates biochemical reactions by binding to the substrate and thereby lowering the activation energy.It binds to the sustrate temporarily only and hence is not changed in the reaction but retrieved.As enzymes affect the forward and reverse reaction rates equally like non-enzyme or inorganic catalysts,it does not change the equilibrium constant of the reaction.

As delta G or free energy depends on keq or equilibrium constant, so it does not get altered.

delta G=-RT ln keq

However,delta S or entropy change depends on product types and also delta H on the reaction,whether it is exergonic or endergonic.(specific for reaction types)

same for non enzymatic catalyst

Increase

decrease

No change

No way to tell

Rate of forward rxn

Rate of backward rxn

Activation energy

Delta H

Delta S

Delta G