Enzyme Kinetics: Problem Set#5 Question #4
This page simulates the outcomes of initial velocity measurements on the enzyme, chymotrypsin. Chymotrypsin hydrolyzes peptide bonds after large hydrophobic residues. The enzyme also catalyzes the hydrolysis of amino acid esters. For this question, the reaction catalyzed is:
p-nitrophenyl-tyrosine --> p-nitrophenol + tyrosine
The reaction rate is measured by following the appearance of the yellow p-nitrophenol product. Background on enzyme kinetics can be found in the Lecture 14 notes.
- Chymotrypsin is a single subunit protein with Mr = 25,000 Da.
You have a 1.5 mg/ml solution of chymotrypsin.
You can add any concentration of the ester substrate to the reaction tube.
- a) Use the resulting values of vo to calculate 1/vo and 1/[S];
- b) Plot the data on a double reciprocal plot;
- c) Determine KM and Vmax;
- d) Calculate kcat, the enzyme turnover number;
- e) Submit your data, calculations, and the graph that yields KM and Vmax.
(Each calculated vo value has a small "experimental error" added to it.)
Use the steps described on Topic #4: Enzyme Kinetics Calculations to solve this problem.
Hint: For your submitted graph, ignore the data <10% and >90% Vmax when drawing a line. These values will have more relative error and they are not necessary to determine an accurate slope and intercept on the reciprocal plot.
Print an Answer Form for submitting your solution.
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