Chemical Forums
Specialty Chemistry Forums => Biochemistry and Chemical Biology Forum => Topic started by: jpollack97 on March 21, 2017, 09:20:17 PM
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http://imgur.com/a/7BaWH
The full question is in the link above. The only correction is that 21.56mg/mL is the enzyme concentration not 0.02156mg/mL. I have the volume of stock enzyme solution in uL which is 464uL for assays 1-5. I am not sure how to get the volume of stock substrate solution.
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This is a straightforward dilution calculation. Do you know the general formula for this?
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This is a straightforward dilution calculation. Do you know the general formula for this?
Yeah I used m1v1=m2v2 and did this:
(301.26g/mol)(0.000125mole/L)(1L/1000mL)(0.464mL)=(10mg/mL)(V2)
i get 0.001747mL=0.000001747uL of stock substrate solution. the answer is very small so the calculation is wrong and i cant figure out why. do i even need molar mass for this? it was hard to find online
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You may be making several mistakes, but it is difficult to tell. I strongly suggest breaking your calculations in to steps. In the first step convert the stock concentration from mg/mL into a molarity (M). To do this you do need the molecular weight. Next convert the stock concentration into millimolar (mM). At this point you are ready to use C1V1 = C2V2, because the units of concentration of the stock solution are the same as the units of concentration in the assay, namely millimoles per liter.
Finally, common mistake in applying this formula is to use the wrong volumes. Your use of 0.464 mL makes no physical sense. I sometimes ask students to draw a picture of the dilution, so that they can more easily see what is happening.
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my calculations are correct, i just converted 464uL to mL so the units match and cancel out.
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0.001747mL=0.000001747uL
No idea about other parts, but this is painfully wrong at the first sight.
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my calculations are correct, i just converted 464uL to mL so the units match and cancel out.
Using this volume does not make physical sense. This is why I suggested that you draw a picture of the dilution of the stock substrate solution into the assay solution. What is the volume of the assay?