You might want to look into the Microcon-SCX from Amicon. Even at the
low amounts of digest you're dealing with, you should be able to get it
cleaned up and sufficiently recovered and concentrated.
Mike Klein
Amgen, Inc.
> ----------
> From:
> Erland.Holmberg@eu.pnu.com[SMTP:Erland.Holmberg@eu.pnu.com]
> Sent: Monday, June 29, 1998 9:03 AM
> To: Recipients of ABRF List
> Subject: Digest: PEG
>
> Dear ABRF-members,
>
> we have encountered problems with the MS-analysis of some samples
> from
> in-gel digestions of 2DE spots. These samples (1-5 pmoles) contain
> components eluting from the HPLC separation as a ladder in the
> middle of
> the gradient (Pepmap. C180.3x250 mm, 30-45% ACN). The components
> have an
> increasing mass difference of 44 Da relative each other. We have
> identified them to originate from non-ionic detergents containing
> PEG
> moieties (e.g. Triton X-100).
>
> I searched the ABRF archive and found that byproducts (aldehyde and
> peroxide) in PEG products also might cause problems with the
> digestion
> itself.
> We have tried to remove these agents using an NID-trap (Michrom
> Bioresources). In our hands, however, this separation doesn't seem
> to
> work too well for digest mixures. The peptides seems to go with the
> void.
>
> If you need to use non-ionic detergents, does anyone have any good
> protocols for removing the problems we see, e.g. removing non-ionic
> detergents and/or byproducts therof, from digestion mixures?
>
> ----------------------------------
> Erland Holmberg, PhD
> Manager, Protein Identification
> Research, Pharmacia & Upjohn, Sweden Tel: +46 8 695 9094
> Mobile +46 8 817 0619
> Fax: +46 8 695 7640
>
> e-mail:erland.holmberg@eu.pnu.com
> ----------------------------------
>