User:Monika Gasiorek/Notebook/CHEM-571 2014F/2015/01/28

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January 28th, 2015

Pepsin Reaction Preparation

The 50 - 5 mL samples of AuNPs were observed for the formation of fiber aggregates. The presence of these fibers was confirmed.

8 of these 5 mL samples were taken and the supernatant solution was drained using a disposable pipet. Not all 5 mL of solution was removed from each test tube --> While majority of the fibers stuck to the walls of the glass tubes, some were free in solution and were susceptible to being sucked up with the supernatant.

NOTE: Concentrations of pepsin were thus altered from the values intended, which are demonstrated below.

After removing the supernatant, a proper amount of pepsin in 5 mM Tris*HCl/0.2 M NaCl (pH 8) buffer was added to each of the 8 samples with the volumes and concentrations specified below:


1. 0.00530 g of pepsin

  • Add 1.325 mL of buffer X 2
    • [Pepsin] = 57.8 μM

Reaction time: 4 hours

2. 0.00398 g of pepsin

  • Add 1 mL of buffer X 2
    • [Pepsin] = 57.5 μM

Reaction time: 6 days


3. 0.00391 g of pepsin

  • Add 1 mL of buffer, take 0.005 mL and add additional 5 mL of buffer
    • [Pepsin] = 0.12 μM

Reaction time: 4 hours

4. 0.00470 g of pepsin

  • Add 1 mL of buffer, take 0.005 mL and add additional 5 mL of buffer
    • [Pepsin] = 0.14 μM

Reaction time: 6 days


5. 0.00419 g of pepsin

  • Add 1 mL of buffer, take 0.05 mL and add additional 4.95 mL of buffer
    • [Pepsin] = 1.2 μM

Reaction time: 4 hours

6. 0.00465 g of pepsin

  • Add 1 mL of buffer, take 0.05 mL and add additional 4.95 mL of buffer
    • [Pepsin] = 1.4 μM

Reaction time: 6 days


7. 0.00780 g of pepsin

  • Add 2 mL of buffer, take 0.5 mL and add additional 4.5 mL of buffer
    • [Pepsin] = 12.5 μM

Reaction time: 4 hours

8. 0.00584 g of pepsin

  • Add 1.5 mL of buffer, take 0.5 mL and add additional 4.5 mL of buffer
    • [Pepsin] = 12.6 μM

Reaction time: 6 days


All 8 reactions were put on the incubator shaker set to 37°C.

Approximately 2 hours into the reaction, no visible color change was observed.


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