We got the same problem on one MAP peptide showing one single pic by HPLC
and having correct amino acids analysis. We saw 1x115, 2x115 and 3x115
adducts on our peptide by ES MS.
We think that this extra pics correspond to TFA (non covalent) adducts as
we used 0.1% TFA for HPLC purification. This peptide hasn't been
relyophilised with water as we donne usually . We will soon have the answ=
er
as we gave the same sample after lyophilisation. Usually , we saw Na and =
K
adducts.
May be it is the answer.
Fran=E7oise Baleux
institut Pasteur
Paris France
>All you peptide synthesis experts, I need help. I've synthesized two
>31mers, Fastmoc Chemistry, on a ABI 430. They both had either consecutiv=
e
>asps,(4)or a asp-asn sequence. I used .1M HoBT/20%pip in NMP to deprote=
ct.
>Kaiser tests showed no problems.AAcomps look good. I sequenced one and w=
ent
>28 cycles before it washed out. The sequence was perfect. HPLC showed a=
t
>least 95% one peak for one; the other peptide had one large peak with a
>high,very slight shoulder. The problem: MALDI showed two peaks for each
>peptide, one the correct mass and the other about 115mu larger. I have n=
o
>idea what this is or what to do about it. My experience in pepsyn and ma=
ss
>spec is very limited. Any help would be GREATLY appreciated. Thank you,
>Sandie Smith
>
>Sandie Smith
>Protein Microanalysis Facility,
>Institute for Cellular and Molecular Biology
>University of Texas, Austin, Texas 78712
>Email: sandie@mail.utexas.edu
>Phone: 512 471-3741, Fax: 512 471-2149