I've had similar problems when digesting peptides he contaminants were in
the enzymes I was using. that's why if possible use sequencing grade
enzymes.
Amina
Amina S. Woods, Ph.D.
NIDA Intramural Program, NIH
5500 Nathan Schock Drive
Baltimore, MD 21224
Tel: 410-550-1507
Fax: 410-550-2971
e-mail: awoods@intra.nida.nih.gov <mailto:awoods@intra.nida.nih.gov>
-----Original Message-----
From: Association of Biomolecular Resource Facilities
[mailto:abrf-request@aecom.yu.edu]On Behalf Of William H. Vensel
Sent: Friday, March 16, 2001 10:23 AM
To: Recipients of ABRF List
Subject: Contaminating Polymer in MALDI Spectra
Hello,
We are doing peptide mass mapping and have been doing it with success for
about a year. Just recently we began to see what looks like a polymer
with a repeat of 44mu. The range is from a mass of 800 to about 1200. The
disconcerting problem is that it does not appear in all of the samples
making it difficult to trace. We have been using Invitrogen 2-D mini gels
and have been doing all of our sample processing using a DigestPro. The
staining procedure has not changed, the gels are scanned, the spots cut out
and the plugs frozen. Gels from spots that gave "polymer" free spectra
previously suddenly have "polymer". The source is not the matrix
preparation, and when adjacent spots from the same gel are analyzed one
will sometimes have the "polymer" and the other not. One possibility that
has not been checked is contamination of the target. That will be done
today. If anyone has any suggestions or has seen such a contaminant
please let me know.
I will post all responses after removing identifiers. If any one would
like to see a spectrum I will be glad to E-mail one either as a gif or as a
file that can be viewed using MoverZ.
Thank you,
Bill Vensel
USDA/WRRC
Albany, CA
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