If you notice, I did not say 250 kDa DNA. It will have to be a shorter DNA, that *behaves* on size exclusion like a 250 kDa protein. I once worked out the ratio, but don't remember what it ended up being, anymore :)
The advantage is that you can get these standards easily enough in a huge range of sizes. The disadvantage naturally is that it's not protein, so one is not comparing apples to apples. However, SEC as a method of accurate size determination (as opposed to practical separation) has many deficiencies anyway, unless one is doing SEC under denaturing conditions with perfect calibration. Artem On Sun, Feb 20, 2011 at 2:21 PM, Filip Van Petegem < filip.vanpete...@gmail.com> wrote: > But this wouldn't correspond to a globular form; 250kDa DNA will appear > larger than a 250kDa globular protein. > > On Sat, Feb 19, 2011 at 5:25 PM, Artem Evdokimov < > artem.evdoki...@gmail.com> wrote: > >> A sufficiently long piece of DNA works OK. >> >> >> On Sat, Feb 19, 2011 at 6:47 PM, Alexandra Deaconescu < >> deac...@brandeis.edu> wrote: >> >>> Dear ccp4bb enthusiasts: >>> >>> A question unrelated to ccp4: can anyone recommend a good 250 kDa >>> standard for gel filtration that is commercially available? It could be a >>> single polypeptide or an oligomer too... >>> >>> Thanks a lot! >>> >>> Bests, >>> Alex >>> >> >> > > > -- > Filip Van Petegem, PhD > Assistant Professor > The University of British Columbia > Dept. of Biochemistry and Molecular Biology > 2350 Health Sciences Mall - Rm 2.356 > Vancouver, V6T 1Z3 > > phone: +1 604 827 4267 > email: filip.vanpete...@gmail.com > http://crg.ubc.ca/VanPetegem/ >
