I bought an enzyme with the following characteristics: 10.20 units/mg protein, 51.55 mg, and 9.70 units/mg solid. I will need 5 units in my final enzyme assay, where the final volumen will be 300 ul, and I will add 15 ul of the stock solution of the enzyme. How do I prepare the stock solution?
Thank you for your help.
You need 5 units, to be added in 15 µl, which is 0.333 U/µl for the 20X stock solution.
(0.333 U/µl)/(9.70 U/mg) = 0.0343 mg/µl = 34.3 mg/ml
So the 20X stock solution should have a concentration of 34.3 mg of solid per ml.
0.015 ml x 34.3 mg/ml x 9.7 U/mg = 5 U
Dear Adam B Shapiro ,
Thank you for your reply, but actually, I want to have 5 units in the final volume, which is 300 ul. So I think it should be 100 units added in 15 ul? Does it make sense?
If you add 100 units in 15 µl, you will have 100 units in the final volume of 300 µl. You may be confusing the number of units with the concentration in units/ml.
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