Regarding our missing His and Lys problems. Thanks to Tim regarding the
missing His in the first cycle, his response was posted to the bulletin board.
The missing lysines stumped everyone except Mark Aldridge at Agilent. It seems
if you are using the Peptide method and have "old" S2/3 and/or S3 and have a
lysine less than 10 residues in...you will see it. If your lysine is more than
10 residues in, you will not see it as recovery of lysines is greatly
compromised by the "old" reagents. We replaced S3 with fresh stuff and lo and
behold all the "missing" lysines made an appearance!! The first of five
lysines in our problem peptide is located at residue 15... Mark's
recommendation is that S2/3 and S3 should be discarded after 90 days from
receipt.
Weather inconsequential: I would like to suggest venues for the EB's proposed
two new workshops. Berkeley is due east of the Golden Gate and is thus
directly exposed to Pacific ocean winds. The Berkeley marina has a nice park
that would be perfect for the 1/2 day kiteflying workshop. The Cal campus with
its towering redwoods would be appropriate for the 3 1/2 day kite retrieval
workshop. Now really, Omaha!!??
Jim
---------------------- Forwarded by Jim Bloom/BRKL/PH/US/BAYER on 03/13/2000
08:34 AM ---------------------------
Jim Bloom
03/08/2000 11:06 AM
To: abrf@aecom.yu.edu@internet
cc:
Subject: Edman sequencing problem
I would like to thank the many people who so kindly advised me on my last
problem. I will push my luck and ask another!!
We recently purchased a synthesized peptide that the vendor checked by MS and
AAA....all hunkie dory. We checked the mass in house and it was fine and then
we sequenced the peptide. The peptide should contain a His at the N-terminal
that we do not see...residue 2 is a Ser as predicted but we also see His. So
first question is why don't we see His in cycle one but see "carry over" His in
cycle 2? Next question....the peptide contains 5 Lys as per the vendors AAA
but at the positions that should contain lysine we see "nothing". We are
using an HP/Agilent machine and we are aware that bad S2A is floating around
BUT we are using ABI S2A and peptide samples before this one all had lysines
appearing normally where they are supposed to be.
We are not really up on peptide synthesis and possible pitfalls....so,
is it possible that during synthesis His and Lys are somehow "weird" such that
Edman doesn't see them? MS and AAA wise however things look ok. Should we
complain to the vendor?
weather inconsequential: no problems with kites in trees...is there something
in the ABRF charter about distinguished members and tree climbing??
Jim Bloom
Bayer Corp
Berkeley
510-705-7760
jim.bloom.b@bayer.com
This archive was generated by hypermail 2b29 : Mon Mar 27 2000 - 11:29:46 EST