Bands of interest were excised from Coomassie blue-stained gels
and de-stained with 25 mM ammonium bicarbonate in 50% acetonitrile/
50% water. The gel was dehydrated by addition of absolute
acetonitrile (covering each gel piece) for 5 min. The acetonitrile was
removed and the gel rehydrated with 100 mM ammonium bicarbonate
(10 min). Then, the gel was dehydrated with acetonitrile
(5 min), the acetonitrile removed and the sample dried in a Speed-
Vac for 2e3 min. The sample was rehydrated with 10 mM dithiothreitol
(DTT) and incubated for 30 min at room temperature
(22e24 C), then alkylated with 50mMiodoacetamide for 30 min at
room temperature, and then washed in 100 mM ammonium bicarbonate.
Once the iodoacetamide had been removed, the samplewent
through 3 further rounds of dehydrationerehydration (100%
acetonitrilee100 mM ammonium bicarbonate). After the final
dehydration, the sample was dried in a Speed-Vac. The gel spot was
rehydrated (with a 12.5 ng/ml solution of trypsin) in ice-cold 50mM
ammonium bicarbonate.