User:Eleni N. Kalivas/Notebook/CHEM-571/2013/09/24

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(Objective)
Current revision (12:28, 1 October 2013) (view source)
(Protocol)
 
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### Measure the absorption spectrum (specifically note 280nm) in order to determine the protein concentration in solution. Use the stock hemoglobin solution as your reference
### Measure the absorption spectrum (specifically note 280nm) in order to determine the protein concentration in solution. Use the stock hemoglobin solution as your reference
# Repeat Step 3 every 30 minutes for 2 hours.
# Repeat Step 3 every 30 minutes for 2 hours.
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==UV vis==
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Absorbance Spectra of hemoglobin with pepsin
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[[Image:Pepsin09242013zem.png|750px]]

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Objective

Analyze the catalytic activity of pepsin in the presence and absence of pepstatin. The data collected today will be compared to our data taken from pepsin-AuNPs.

Protocol

The following protocol was taken from Matt Hartings

We will allow the pepsin cleavage of hemoglobin to proceed for two hours with aliquots taken and analyzed every 1/2 hour. We will also run parallel reactions with different concentrations of pepstatin (pepsin inhibitor) present. We will save our aliquots for analysis tomorrow using SDS-PAGE.

  1. Combine 5 mL of the hemoglobin solution with the appropriate amount of pepsin (the final concentration should be 2 nM).
    1. Do the same only with an appropriate amount of pepstatin added. (Each group will use a different concentration of pepstatin. We'll want 2 nM, 20 nM, 0.2uM, 2uM, and 20uM)
  2. Incubate these solutions at 37C (in the incubator shaker)
  3. After 30 minutes, remove two samples, as instructed below, for analysis today and tomorrow.
    1. Prepare a sample for SDS-PAGE tomorrow
      1. Remove 10uL of the reaction sample and dilute to 1mL with the Glycine-HCl buffer
      2. Take 10uL of this diluted sample and mix with 10uL of the SDS-PAGE running buffer
      3. Store all of your SDS-PAGE samples in the fridge overnight.
    2. Prepare a sample for UV-Vis analysis today
      1. Remove 0.75mL of the reaction sample and add 0.75mL of 1.7M perchloric acid to precipitate the remaining hemoglobin
      2. After this sample sits for 1 hour, centrifuge for 15 minutes (organize centrifuge time with the other groups) in order to remove solid (uncleaved hemoglobin) from solution
      3. Measure the absorption spectrum (specifically note 280nm) in order to determine the protein concentration in solution. Use the stock hemoglobin solution as your reference
  4. Repeat Step 3 every 30 minutes for 2 hours.

UV vis

Absorbance Spectra of hemoglobin with pepsin



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