Re: MS - target cleaning etc.
Kris.Gevaert (krgev@medusa.rug.ac.be)
Fri, 20 Feb 1998 08:26:33 +0100
>Dear ABRF community,
>Since about 6 weeks we are in the MALDI-TOF business. Great fun and
>impressive sensitivity - a lot of important data has been generated. Sofar
>mainly on synthetic and proteolytic peptides, the latter from both
>Coomassie- and silver-stained gels.
>We have a lot of questions; I'll ask the two most urgent ones:
>1. How to clean the stainless steel targets? Our Bruker Biflex is equipped
>with the 26 sample circular holder. We have followed various protocols -
>none removes absolutely everything. "Ol' history" is becoming annoying!
>2. I've learnt that internal calibration gives highest accuracy; the
>autodig products of proteolytic enzymes should be ideal. Anyone knows if
>the Promega modified trypsin, with its methylated Lys side chains, produces
>any useful "calibration standards"? Same for Achromobacter lyticus LysC?
> Thanks /Ulf
>******************************************************
>Ulf Hellman, Ph. D.
>Ludwig Institute for Cancer Research :
>Box 595
>S-751 24 Uppsala
>Sweden
>
>Phone +46 18 160423
>Fax +46 18 160420
>E-mail ulf.hellman@licr.uu.se
>Lab's home page: http://www.licr.uu.se
Ulf,
We have the same mass spec and use similar targets. The best way to clean
your targets, at least to our knowledge, is to sonicate them in
water/methanol/formic acid (1/1/1) for about 10 min, rinsing with methanol
and drying in a nitrogen stream. One thing you should keep in mind is that
at the back of the targets is a magnet device which contains copper. This
should be removed each time you sonicate the targets in an acidic solution
since we have seen deposition of copper onto the target!
As for you second question the Promega modified trypsin does have a number
of autodigestion products; if I am not mistaking there's one at 842 da and
one at 2283 da.
Hope this will be of any help.
Kris
Kris Gevaert
University of Ghent
Flanders Interuniversity Institute for Biotechnology (V.I.B.)
Dept. of Medical Protein Chemistry
K.L. Ledeganckstraat 35
B-9000 Ghent
Belgium
Europe
Tel.: + 32 - 9 264 52 91
Fax: + 32 - 9 264 52 93
E-mail: krgev@gengenp.rug.ac.be or krgev@medusa.rug.ac.be