# [Protein-analysis] Re: Help with calculations for specific activity

professorgunz via proteins%40net.bio.net (by mready from austin.rr.com)
Wed Oct 15 16:56:38 EST 2008

```DK wrote:
> In article <mailman.209.1222814664.29717.proteins from net.bio.net>, "Fasulo, Lisa M" <lisa.m.fasulo from pfizer.com> wrote:
>> I am trying to calculate the specific activity of my [3H]-ligand but
>> don't know how to do it.  The package insert for my radioligand states
>> that the Specific Activity is 200 mCi/g but I need to know what the
>> Specific Activity is in Ci/mmol.  How do I calculate this?  The
>> molecular weight of the radioligand is 463.6 g/mol.  Can anyone walk me
>> through the calculations to give the specific activity in Ci/mmol?  The
>> only other info I have is the concentration of the radioligand which is
>> 1mCi/mL.
>
> compound is 92.72 mM.
>
> This is very basic, Lisa. Do something urgent to figure it out
> yourself. Or do yourself and your company a favour and quit.
> It is THAT important!
>
> Hope the hint above helps.
>
>
Actually, the SA is 92.72 _milli_Curies/mmol and the concentration is
10.785 mM (to probably more significant figures than it deserves).

.2 Ci/g x 463.6 g/mol = 92.72 Ci/mol = 92.72 mCi/mmol

(1 mCi/ml)/(92.72 mCi/mmol) = .010875 mmol/ml = 10.875 mmol/liter

Not sure which people need to do everyone a favor and quit.  Yeesh...
```