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Subject: Protein Sequencing
Author: trobinson@pdl.com (Tom Robinson) at INTERNET
Date: 3/29/99 4:36 PM
I have a question about N-terminal protein sequencing. The known
N-terminal sequence of the protein I am sequencing is DIQM.... In the
fourth cycle I see the expected PTH-methionine peak, but I also see a
smaller peak eluting at the retention time of PTH-lysine. I get about 500
picomoles of methionine and 100 picomoles of "lysine" in cycle 4. I am
using an HP 241 sequencer. I have tried sequencing another protein with a
methionine residue and observed the same thing. Can methionine be
converted to lysine or something that elutes at the same time as lysine by
the cleavage/conversion chemistry? Does anyone know the cause of this?
Could old reagents cause this?
Thanks,
Tom
Tom Robinson
Protein Design Labs, Inc.