Enzyme Assay Using a standard curve to determine the concentration of enzyme in an unknown sample.
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Transcript of Enzyme Assay Using a standard curve to determine the concentration of enzyme in an unknown sample.
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Enzyme AssayUsing a standard curve to determine the concentration of enzyme in an unknown sample.
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Examples of Standard CurvesWhat is the X axis?What is the Y axis?
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How can a curve be used?Predict unknown concentration
when you test for the independent variable.
◦“Assay”: analytic procedure to quantitatively measure the amount of activity in a sample.
◦Use the results of the “assay” to predict unknown concentration.
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Our Model SystemCatalase:
◦You are working for a drug company and you want to make a “generic” of the enzyme based drug another company produces.
◦You must determine how much of the active ingredient is present in the drug.
◦Your research in the papers suggests the concentration is between
.1 and 10% (mass (g)/volume (ml))◦The closer to the exact amount you can
come, the better your generic will work!
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Model SystemWhat does catalase do?
◦H2O2 H2O + O2
◦What can you “assay” for?
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Methods and MaterialsShared Materials:
◦Bottles of 6% and 3% H2O2
◦2 blenders (must be cleaned with soap at the end!)
◦2 electronic balancesIndividual Materials:
◦~25 g liver—source of catalase◦Conical tubes for reactions◦2-disposable pipettes◦2-1mL graduated pipettes◦Weigh boats◦50 mL grad cylinder◦250 mL beaker
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Importance of variables & controlsCould I design my own method to
test the same IV and DV?
FOCUS: What would I need to know to exactly repeat your methods?
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Your job (Monday and Tuesday)Figure out the role of catalase in cell and
why it is essential in cells.Design a standard curve to assay for the
concentration of catalase in an unknown sample.
Determine what type of best fit line fits your data.
Estimate the concentration.Suggest a second run based on the
information you found to further refine your value.
Connect the methods for this lab to a real-world problem.
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Is your curve usable?Is your curve linear? Curved? How
do you know if the curve you’ve chosen is acceptable?◦Calculate “Y hat”
This is the Y value for each X if the equation is used (rather than having your values be plotted)
◦Residual = Yobserved-Yhat
◦Graph residuals vs. X. If there is no pattern, then the regression line captures the overall pattern.
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