Question

B 2 ml 500 ul 1 1.25 ml 500 ul 1 ml Reagent HO 300 mM NaPO4 pH 7.4 250 uM DCIP 60 mM succinate 60 mM malonate Tissue Homogenate (add this just before you take the initial reading) 2 750 ul 500 ul 1 ml 500 ul 3 700 ul 500 ul 1 ml 500 ul 50 ul 4 650 ul 500 ul 1 ml 500 ul 100 ul 5 550 ul 500 ul 1 ml 500 ul 200 ul 500 ul 250 ul 250 ul 250 ul 250 ul 250 ul Calculate the final concentration of malonate present in reactions 2-5. Show your work here and place your results in the table below. Tube (malonate concentration] 1 N 3 4 5

Answer 1

The malonate stock used here is 60 mM.

In the tubes 1 and 2 there is no malonate added, so the concentration of malonate in these tube would be zero.

In order to find the malonate concentrations in the remaining tubes (3 to 5) we need to know the total reaction volume first. This is obtained by adding up the volumes listed for each tube. We can see that the reaction volume here is 3 mL.

We can find the concentration of malonate by finding the dilution factor in each tube and then dividing the stock concentration by the dilution factor.

For Tube 3: 50 uLof 60 mM malonate is added in a final reaction volume of 3 mL or 3000 uL. Here, malonate is diluted 3000 / 50 = 60 times

The final concentration of malonate here is: 60 / 60 = 1 mM malonate.

For Tube 4: 100 uL of 60 mM stock is added in a final reaction volume of 3000 uL.

Dilution factor = 3000 / 100 = 30

final malonate concentration = 60 / 30 = 2 mM

For tube 5: 200 uL of 60 mM stock is added in a total reaction volume of 3000 uL

Dilution factor = 3000 / 200 = 15

final malonate concentration = 60 / 15 = 4 mM

Therefore, the malonate concentrations used in tubes 3, 4 and 5 are 1 mM, 2 mM and 4 mM respectively.