methylation

[Oliver Schmidt]

I have a 20aa peptide which is subject to methylation through an unknown
methyltransferase.
There are various positions in this peptide  which are possible targets for
methylation.
Does anyone know a method to identify which aminoacid is methylated in a
20aa peptide of known sequence?
(Mutation of the possible target sites would be really expensive...)
Is it possible to check this with MALDI-TOF or is there another way for such
a small peptide?

Thanks,
Oli