>We are a group in Gothenburg/Sweden interested in
>mucin oligosaccharides. For the moment we are investigating the sulfated
>oligosaccharides by mass spectrometry as peracetylated derivates, but we are a
>little conspicius about what the deivatisation will do to oligosaccharide
>species containing both sialic acid and sulfate. We are using the procedure
>with pyridine/acetic acid anhydride as reagents. We are also interested in
>adopting a permethylation procedure for the sulfated oligosaccharides both with
>and without sialic acid, but procedure proposed by Ciucanu/Kerek have so far
>proved unfruitful.
>_____________________________________________________________
With respect to your queries, please refer to our paper in Carbohydr Res :
Khoo, K.-H., Morris, H.R., McDowell, R.A., Dell, A., Maccarana, M. and
Lindahl, U. (1993) FABMS/derivatisation strategies for the analysis of
heparin-derived oligosaccharides. Carbohydr. Res., 244, 205-223.
It is unclear whether the NaOH method by Ciucanu and Kerek will
successfully methylate sulphated samples but one known problem is in the
subsequent clean-up. Should the sulphate(s) be retained, the methylated
samples may go into the aqueous phase during the chloroform/water
partitioning step. Methylating sialic acid containing oligosaccharides
should not be a problem.
Khoo
