You have 50 uL of a 150 nguL plasmid stock solution A partic

You have 50 uL of a 150 ng/uL plasmid stock solution. A particular transformation protocol suggests you add 5 ul of a plasmid solution delivering a total of 10 ng plasmid DNA. What is the best way to go about setting up a new diluted stock? Plasmid stock uL 20. uL ul Total volume

Solution

Answer:

This calculation is very common for DH10Bac trasformation for Blue/White colony selection and preparation of bacmids.

Stock: concentration = 150 ng/microL, volume = 50 microL

We require 10 ng plasmid in the final 5 microL of plasmid solution. So, we need to prepare a 10 ng/microL diluted stock from which if we take 1 microL and add to 4 microL water, the final solution will contain 10 ng of DNA.

Using V1S1 = V2S2, we get

150 * V1= 100* 10 (We want to prepare a 100microL stock of 10ng/microL final concentration)

Therefore, V1 = 1000/150 = 6.67 microL

So, to 93.33 microL water, we need to add 6.67 microL of plasmid from the 150 ng/microL stock to have a final concentration of 10 ng/microL.

Thus, the final calculation:

Plasmid stock = 1 microL (from the diluted stock of 10 ng/microL)

H2O = 4 microL

Total = 5 microL (This contains 10 ng of the plasmid DNA required for transformation)