Digest

Erland Holmberg (Erland.Holmberg@eu.pnu.com)
Mon, 29 Jun 1998 17:57:42 +0200

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?

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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
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