# enzyme activity rate question

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Posts
• #8112
portugal
Participant

The following data was collected in an experiment investigating the activity of a protease, trypsin. The activity of trypsin in breaking down a small polypeptide chain was monitored by determining the concentration of the polypeptide in solution (in Molar units) over time. The results are shown below. Graph these results and determine the rate of reaction. Time (mins) Polypeptide concentration (mM)
0 =100
1 =99.5
2 =99.5
5 =98
10 =97
15 =94
Select the option below that is closest to your answer (within 20%).
a. 0.7 mM/min

b. 1.1 mM/min

c. 2.4 mM/min

d. 4.1 mM/min

e. 7.1 mM/min

f. 12.0 mM/min

g. None of these values is close to my answer.

• #75303
MrMistery
Participant

well you plot one against the other and you should get a line. Where are you having difficulties?

• #75317
portugal
Participant

My answer is something like 0.43millimoles/min and i just wanted to see if any1 else was getting the same answer as that. would you be able to check if you get the same answer please

• #75356
portugal
Participant

i cant believe no one can help me with this question at all, i need help desperately i got a mid session on in 2 weeks and these type of questions will be in there could some one go through the working and post a solution please

• #75375
blcr11
Participant

It looks to me like there’s about a 2 minute lag period and then the reaction is (roughly) linear out to 15 minutes, anyway. The slope of the line is about 0.4 mM peptide digested/min . The only possible answer would be 0.7 mM/min, but +/- 20% of 0.7 is (0.56, 0.84) so my answer is technically g) none of the above. I don’t know how seriously you’re supposed to take the +/- 20%, or if 0.7 is really close enough.

Should also point out that mM/minute is not your usual unit of activity. Usually it is moles (or mmoles or micromoles) converted per unit time.

• #75404
sdekivit
Participant

a very rough estimation of the rate of reaction is 6/15 = 0.4 mM / min