gel electrophoresis of peptides...

Dr I.P. Woodrow woodie at liverpool.ac.uk
Thu Jul 11 08:49:19 EST 1996


In article <4s19qb$guv at deft.cc.purdue.edu>, wilkinst at deft.cc.purdue.edu (Thomas Wilkinson) writes:
> Newsgroups: bionet.molecules.peptides
> Subject: gel electrophoresis of peptides...
> Summary: 
> Followup-To: 
> Distribution: world
> Organization: Purdue University Computing Center
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> 
> 
> Hello,
> 
> I was wondering if somebody had some experience with SDS gel electrophoresis of
> peptides.  I have a sample that I would like to analyze to see if it contains
> a short (12-residue) peptide, molecular weight = 1462.
> 
> The sample is not some mixture of many species...the sample to be analyzed
> either has the 12-mer, or else the sample contains no peptide whatsoever.  Thus,
> this gel should be really easy to interpret.  I also have a similar sample that
> I would like to analyze for peptide content, except in this case I am looking
> for the presence or absence of a 33-residue peptide (MW = 3487).
> 
> I would like to run these samples out on an SDS gel, and then coomassie-stain.  
> My question is that I don't know what the optimal percentage of polyacrylamide 
> would be for this task.  What percent gel is best?  Is gel electrophoresis of
> peptides commonly done?  Your suggestions are much appreciated.
> 
> thanks,
> 
> tom
> 

Is there any particular reason why you need to separate out the peptide 
anyway? If this is the only component which you will find, then all you need 
to is to do a protein assay. I believe I am right in thinking that the 
Bradford assay works by binding to the peptide bond, so you shouldn't have
any trouble seeing small peptides. Alternatively you could try using amido 
black which I know stains small peptides as I have just used it for 7-15
residue small peptides myself. I did dig out an old reference for some protein 
assay using amido black from years ago, although their technique did seem very
long winded. Let me know if you need this, or any other help.

GOOD LUCK!

Iain




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