Contaminant peaks in this type of analysis typically come from either trypsin
autolytic digestion or from keratin contamination. The most comprehesive list
of the exact masses of these contaminant peaks that I have seen can be found in
K. Parker et al., Electrophoresis, 19 (1998) 1920-1932. Herein, is listed a
table of "unassigned peptides upon autodigestion." Using the Promega modified
trypsin at 20ug/mL, one presumably sees masses of modified tryptic autolytic
peaks. The masses listed are:
870.542
1940.930
2221,126
2225.111
2239.140
2807.300
The 2225 and 2239 peaks are presumed to be the methylated and dimethylated forms
of the sequence LGEHNIDVLEGNEQFINAAK, respectively. The others are often
observed but not identified.
The 2461 peak that you see does not match any observed autolytic or keratin
peaks referenced in this paper.
Sincerely,
Dale
********************************************
Dale H. Patterson, Ph.D.
Product Line Manager, Contract Research
PerSeptive Biosystems
500 Old Connecticut Path
Framingham, MA 10701
phone (508) 383-7819
fax (508) 383-7212
email: Dale_Patterson@pbio.com
*********************************************
---------------------- Forwarded by Dale Patterson/HQProdDev/PBIO on 01/19/99
02:44 PM ---------------------------
HAIYING CHEN <Haiying.Chen@dupontpharma.com> on 01/19/99 11:52:23 AM
To: Recipients of ABRF List <abrf@aecom.yu.edu>
cc: (bcc: Dale Patterson/HQProdDev/PBIO)
Subject: in-gel digestion
Dear ABRF,
Recently I tried in-gel digestion of several 2D gel protein spots with trypsin.
Several peaks with masses of 1941.46, 2239.38, 2461.19 and 2807.45 from Maldi-Ms
data appear to be contaminations. However I don't know where they come from.
Has anyone had these results before? And their sources?
Thanks.
Haiying Chen