Has anyone used fluorescein-5-maleimide to label a peptide?

Roger Murphy murphy_r at licre.ludwig.edu.au
Wed Apr 1 01:18:56 EST 1998

A friendly MALDI mas spectroscopist will answer this question a lot faster!


In article <neil.pomroy-3103981115070001 at>, 
neil.pomroy at utoronto.ca (Neil Pomroy) wrote:
>Hi Kate,
>Are you sure your peptide is in the reduced state?  I don't think
>maleimides will react with disulfides.  Try running an SDS-PAGE, one lane
>with your peptide, one with your peptide that has been incubatied in a
>reducing buffer (eg 10 mM dithiothreitol, pH 7+) to see if your peptide is
>a disulfide-bonded dimer.  If it is, you'll have to reduce it and then
>either get rid of the DTT (eg by dialysis) before reacting, or add a
>significant excess of the maleimide (more than the DTT concentration).

Roger Murphy, Ph.D.
Biological Production Facility
Ludwig Institute for Cancer Research
Austin & Repatriation Medical Centre
Studley Road,
Heidelberg,  Vic. 3084

Tel  61-3-94965463
Fax  61-3-94965436
Email murphy_r at licre.ludwig.edu.au

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