Posted 05 October 2011 - 07:45 PM
Posted 05 October 2011 - 10:56 PM
According to this paper (http://www.pnas.org/...3/5914.full.pdf), one unit of IL-2 is approx 3ng. But here (http://www.ncbi.nlm....l00110-0135.pdf) it says one unit is 10 x the reciprocal value of the 50% activity titre.
So the first thing you need to do is tell us what you are using as a definition of unit.
Posted 06 October 2011 - 05:40 AM
Posted 06 October 2011 - 07:22 AM
Now, think about it. 2.5x10^5 U/µg = 2.5x10^5U in 1µg so in 20µg you have = 2.5x10^5x20 = 50x10^5U
You say you need 100U/ml so you just need to divide your total Units by 100 = 50x10^5 / 100 = 50000ml = 50L
Another way of doing this will be to calculate how many ug you need to have 100U if you know there are 5x10^5U/µg.
100U / 5x10^5U/µg = 0.0005µg
Now, I'm having problems believing that you have to resuspend your sample in 50L and it'll be pretty much impossible to measure 0.0005µg.
Having had a quick look at the R&D website, they recommend reconstituting at 100µg/ml in PBS containing 0.1%BSA.
So, you need to resuspend your 20µg in 200µl for it to be at 100µg/ml.
Following the same logic as above => 100µg/ml x 5x10^5U/µg = 5x10^7U/µl = 5x10^4U/ml from this you can easily prepare your required 100U/ml by diluting 500 fold.
Just used C1V1 = C2V2 to calculate how much you need of this solution to make your 100U/ml.