# Enzyme Units RNaseA - (Jul/25/2012 )

Hi,

^{−1}^{<1>"}

V1 = (0.01 / 70) x 2000 = 0.285ul

This may be completely wrong but I'm not sure how else to work this out.

Thanks,

Ben W.

this is not a c1v1=c2v2 problem. you are not looking for a final concentration. you are looking for an absolute amount.

you have a 20mg/ml solution of rnase and the specific activity is 70 units/mg (1400 units/ml). you want 20 units to put into your dna solution. 20/70=0.2857.

you, therefore, want approximately 0.29mg (20.3 units). 20mg/ml=1mg/50ul. 0.29x50=14.5ul.

you want to add ~14.5ul of your 20mg/ml rnase solution to your dna solution.

or you can calculate this way:

20units/1400units/ml=0.014286ml=~14.3ul

Thanks! That's much easier than I was playing it up in my head I think.

But, you put 14.3ul of RNAse independently of volume of DNA solution?, for example I have 500uL of DNA. Should I put 14.3ul? I dont understand that calculation.

Thanks a Lot

But, you put 14.3ul of RNAse independently of volume of DNA solution?, for example I have 500uL of DNA. Should I put 14.3ul? I dont understand that calculation.

Thanks a Lot

the calculation was not to determine final concentration, it was to add a specific mass of enzyme to the solution. this will slightly dilute the sample but will deliver the specific amount of enzyme