Chemical Forums

Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: Albert on October 21, 2005, 06:57:11 AM

Title: Centrifugation, Proteins and molecular weight
Post by: Albert on October 21, 2005, 06:57:11 AM

Hello everybody.
Talking about centrifugation, one of its applications is determining proteins's molecular weight. However it can be used for separating proteins from mitochondria and nuclei (for example). The two procedures are different, I think also for what concerns machinery and time.

Now, here is my question. My professor gave us a test-yourself exercise and one of the statements is:

'In order to separate proteins using centrifugation, a low rate centrifuge is sufficient.'

Is it true or false? In my opinion it is just a matter of which kind of procedure we are talking about.

Title: Re:Centrifugation, Proteins and molecular weight
Post by: Mitch on October 21, 2005, 12:23:12 PM

You just use a centrifugal cut-off filter.

Title: Re:Centrifugation, Proteins and molecular weight
Post by: Albert on October 21, 2005, 12:47:33 PM

Ok, thank you very much.

So, to sum up, for this kind of process a low-rate centrifuge is sufficient...and it doesn't take you too much time, does it?

Title: Re:Centrifugation, Proteins and molecular weight
Post by: Mitch on October 21, 2005, 01:00:34 PM

You put your extract into the centrfugal cut-off filter go read your e-mail and come back.

Title: Re:Centrifugation, Proteins and molecular weight
Post by: Yggdrasil on October 21, 2005, 05:41:42 PM

If you just want to separate components of a mixture (e.g. insoluble cell debris from a cell lysate) then a low rate centrifuge is sufficient.  However, if you want to determine the molecular weight of a protein/separate two proteins of similar molecular weight by equilibrium sedimentation, you need a high-rate centrifuge.