the following procedure is simple and efficient. You should note though
that in most cases, esterification is not really needed for the
identification of peptides by MS. Its main application in this area lies in
the de-novo sequencing of peptides - that is when you need to know exactly
which fragment ion series you are reading. A note of caution concerns
reagent purity. For esterifying sub picomol amounts of digests, make sure
that you use distilled reagents of the highest quality available.
Protocol:
1) Cool 1ml clean and dry Methanol to -20 Celsius in a 2ml tube.
2) Add 100ul of ice-cold acetyl chloride (beware that mixing may be
accompanied by a rather violent reaction and as a result liquid might get
sprayed all over the place - protect hands and eyes !!!).
3) Let reaction mixture warm up to room temperature and use the reagent 10
minutes later.
4) dry you protein digest in a speedvac.
5) Add 2-5ul of the reagent to the dried peptides and incubate for 30
minutes at room temperature.
6) Dry reaction in a speedvac.
7) Do the usual micro clean-up before ES-MS
good luck
Bernhard
Bernhard Kuster, D.Phil.
Research Associate Professor
Protein Interaction Laboratory (PIL)
Department of Molecular Biology
University of Southern Denmark
Campusvej 55
5230 Odense M
Phone: +45-65502474
Fax: +45-65933018
email kuster@cebi.sdu.dk
URL http//www.pil.sdu.dk