I am not entirely sure why is this a problem. At pH 7.5 something with pI of
8.1 is overall positively charged, and thus has to bind acidic resins. If
the protein has acidic residues in 'patches' then it will also bind to basic
resins - but it probably will be binding them weakly. No contradiction,
unless the program says that the protein is eluted from both types of resin
at the same point of the salt gradient.
A.G.E.
<kaj.stenberg at helsinki.fi.invalid> wrote in message
news:a58p3n$5ej$1 at oravannahka.helsinki.fi...
> Two students were playing around with a computer simulation of protein
> purification. They had a protein with a Pi of 8.1, wich was a single
> band on 2D-electroforesis. However, at pH 7.5 the protein was bound both
> to an anion and a cation exchange matrix.
>> Can anyone explain how this is possible and if it could occur in real
> life? I doubt that the program simulates nonspecific binding to the
> matrix?
>> (Sorry about the slightly vague details, I have not seen their results
> myself yet).
>> --
>============================================================================
> Kaj Stenberg, Ph. D
> Department of Biosciences tel. +358-9-191 59682
> Division of Biochemistry fax +358-9-191 59068
> P. O. Box 56, Viikinkaari 5 e-mail: kaj.stenberg at helsinki.fi> FIN-00014 University of Helsinki http://www.helsinki.fi/~kstenber/> Finland
>> This message is environmentally friendly: every bit was created using
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>>============================================================================
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