You have assayed the activity of amylase under two separate NaCl concentration:s

Question

You have assayed the activity of amylase under two separate NaCl concentration:s The starting concentration of your starch solution is 1.75 mg/ml, and 15 ml of starch was combined with 15 ml of buffer before amylase was added to the mixture The following are the average absorbance readings from your three replicates me Absorbance 1.430 1.210 0.920 0.690 0.460 0.414 0.391 0.366 0.346 0.331 0.341 1.580 1.410 1.200 0.978 0.814 0.650 0.486 0.441 0.389 0.356 0.366 4 10 16 18 20 a-b. At the point when 30% of the starch has been degraded, how much starch is left in the flask? Include units with your answer. Round to 1 decimal place a. 10mMM b. 50mM C-d, what are the rates of amylase activity, calculated from the point at which 30% of the starch has been degraded? Include units with your answer. Round to 1 decimal place c. 10mM d. 50mMM e. Under which condition was the measured amylase activity rate highest? (Choose ONE of the following:) 10m M 50m M Cannot be determined from these results f. Based on these results, which of the following is true regarding the optimum Nadl concentration for the enzyme activity? (Choose ONE of the following:) 10mM is the optimum concentration 50mM is the optimum concentration The optimum concentration cannot be determined from these results because only two conditions were measured, and there may be conditions intermediate where to 10mM and 50mM where the activity eaks

Explanation / Answer

At time 0 we get no starch degradation. Now if we look for 30% starch degradation we need to move at the time when 70% absorbance is getting in respect to time 0.

If at time 0 the 10mM concentration has 1.43 OD then the 70% of this OD will tell the 30% degraded starch condition.

At 30% starch degradation the OD of the 10mM sample is = 1.43 x 70%

= 1.001

We can consider time 4 for the solution where 30% starch has degraded.

To calculate how much starch has left in the flask, we will do following steps-

Weight of starch in the flask, formula =V x c

Here V is the volume taken for the preparation of the solution and c is the per ml starch concentration of the stock solution.

Now we know that V = 15 ml

And, c = 1.75 mg/ml

Now the weight of starch in the flask = 15 ml x 1.75 mg/ml

Weight of starch in the flask = 26.25 mg

Now, the net concentration of the starch solution when 15 ml of buffer added can calculate by following steps.

Concentration = W/V

Here W is the weight of the solute and V is the total volume.

Now W = 26.25 mg

Volume V= 15 +15 = 30 ml

Therefore, concentration = 26.25/30 mg/ml

Concentration = 0.875 mg/ml

Part a and b-

Therefore, after 30% degradation the amount of the starch has left in the flask= W x (100-30)%

Here W is the weight of the solute.

Now the amount of the starch has left in the flask= 26.25 mg x 70%

= 18.375 mg

For both NaCl concentrations, the amount of 30% starch degradation is same.

Part c-

30% amylase will degrade at time 4 therefore, the rate of amylase activity =W’/t

Here W’ is the weight of the starch that has been degraded and t is the time.

Therefore, rate of amylase activity = (26.25 – 18.375)/ 4 mg/min

The rate of amylase activity = 1.97 mg/min

Part d-

At 50mM NaCl concentration 30% will degrade at = 1.58 x 70%

= 1.11 OD

Now, the rate of amylase activity = (26.25 – 18.375)/ 4 mg/min

The rate of amylase activity = 1.97 mg/min

The rate is same because both has taken equal time to clear 30% starch solution.

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