Re: MS:
Daniel Hess (Daniel.Hess@fmi.ch)
Thu, 23 Jul 1998 08:29:30 +0200
>Hello everyone!
>
>After "in gel" digestion (trypsin) of an unknown protein
>I measured the full MS spectra of the mixture of peptides with
>Finnigan LCQ.
>I obtained some small peaks and a wonderful "pattern" of 7 peaks.
>Each peak is +14 compared to the previous.
>In detail I have: 608.7 / 622.5 / 636.6 / 650.7 / 664.6 / 678.5 / 692.6
>Moreover every peak is a pattern itself: three peaks which
>the difference is +1, I guess due to the loss of a proton (?).
>(eg: 650.7 / 651.7 / 652.6 intensity decreasing)
>
>Do you have any idea of the origin of this pattern?
>Maybe some contamination during the work?
>
>Thanks in advance!
>
>Federico
>
>--
>Federico Brianza
>Protein Laboratory
>Institute of Molecular Biotechnology
>Beutembergstr. 11, 07745 Jena / Germany
>Tel: +49 3641 656432
>Fax: + 49 3641 656431
Hello Federico,
(eg: 650.7 / 651.7 / 652.6 intensity decreasing) : you are looking at
different isotopic states of a single charged ion, they differ by one Da.
The difference of 14 could be CH2. The molecules you see could be related
to your staining. I have seen 608 at the end of my LC-MS runs from
coomassie stained gels but never from silver!
As a rule: learn your system! Run a few standard proteins and blanks. Check
out what chunk ions you get from the system, ea: trypsin, stain, others.
List them. Try to find ions which are specific for your protein and select
them first for your MSMS!
With best regards Daniel Hess
Dr. Daniel Hess
Friedrich Miescher Institut
Postfach 2543
CH-4002 Basel
Tel.: 061 697 85 44 or 061 697 68 68 FAX: 061 697 3976
e-mail: dhess@fmi.ch