2 - MCB102, Summer 2009 - Problem Set 2 (all questions from...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
MCB102, Summer 2009 - Problem Set 2 (all questions from previous exams) Tuesday and Wednesday lecture questions: 1. You measure the initial rate of an enzyme reaction as a function of substrate concentration in the presence and absence of an inhibitor. The following data are obtained: [S] V 0 (umol/min) V 0 (umol/min) Uninhibited Reaction With Inhibitor Present 0.0001 33 17 0.0002 50 29 0.0005 71 50 0.001 83 67 0.002 91 80 0.005 96 91 0.01 98 95 0.02 99 98 0.05 100 99 0.1 100 100 0.2 100 100 a) What is the Vmax in the absence of inhibitor? b) What is the Km in the absence of inhibitor? c) When [S] = 0.0004, what will V 0 be in the absence of inhibitor? For full credit, show all your work. d) What kind of inhibitor is it likely to be? Explain why you concluded this. 2. You are studying the kinetics of an enzyme, “Enzyme E,” which obeys Michaelis-Menton kinetics You have previously determined that the Km of Enzyme E is 1.0x10 -4 M. In your current set of experiments, you have measured the initial velocity of the enzyme reaction twice, using two different substrate concentrations, but each time using the same concentration of Enzyme E, in an appropriate buffer. Your results are shown here: [S] V o 0.20 M 43 μ M/min 0.02 M 43 μ M/min Explain how these two very different substrate concentrations can produce the same V o . In support of your explanation, show quantitatively how the Michaelis-Mention equation is consistent with/predicts these results.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
3. A mutant form of chymotrypsin contains an asparagine residue, instead of an aspartate residue, at position 102. The proposed arrangement of several amino acids in and near the active site is shown below (A), alongside the structure of the corresponding amino acids in normal chymotrypsin (B). a. Would you expect the catalytic rate of the mutant chymotrypsin to be faster than, slower than, or the same as that of normal chymotrypsin? Mutant catalytic rate will be (circle one): faster slower about the same b. Explain your choice in part ‘a’. In your explanation, refer to specific elements of the catalytic mechanism and how they will or will not be altered. Be precise in your wording and provide a thorough, step-by-step explanation. 4. Chymotrypsin ordinarily functions at about neutral pH. If placed in a solution of pH 5.0, the enzyme shows almost no activity. Chymotrypsin does not denature at this pH - the tertiary structure is perfectly normal. Based on your detailed understanding of the catalytic mechanism of chymotrypsin, explain why
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 09/28/2009 for the course MCB 102 taught by Professor Staff during the Summer '08 term at Berkeley.

Page1 / 5

2 - MCB102, Summer 2009 - Problem Set 2 (all questions from...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online