Glycosylation
is the most complex posttranslational modification of proteins and shows an
enormous structural diversity.1 An important role in many
fundamental biological processes plays fucosylation.2 Thus, the
development of specific tagging methods to visualize the fucosylation of
proteins is of great interest. The biosyntheses of oligo-/polysaccharides and
glycoconjugates are catalysed by enzymes, generally glycosyltransferases (GT). Sugar
nucleotides are activated sugars and substrates of GT.3 Since fucosyltransferases
show a great tolerance to modification in position C6, it is possible to label
a nucleoside diphosphate fucose derivate with dyes in this position. Recently, ATTO
550-labelled guanosinediphosphate-6-amino-6-deoxy-β-L-galactose
was synthesised and has been used successfully as a substrate analogue in a
hFucT-IX-assay. This result proved the tolerance of hFucT-IX towards substrate-modifications
with a dye.4 A very common dye to label antibodies, enzymes and
proteins is fluorescein isothiocyanate (FITC). Therefore, FITC-labelled nucleosidediphosphate-6-amino-6-deoxy-β-L-galactose is a very interesting target structure.
Since the cycloSal approach has been
proven to be a very good method for the formation of modified nucleoside
diphosphate sugars5 it is the means of choice here as well (scheme
1). Here, we report on the synthesis of FITC-labelled nucleosidediphosphate-6-amino-6-deoxy-β-L-galactose, a fluorescence study to compare the
properties of the dye FITC with the FITC-labelled conjugate and its use as a
substrate analogue in comparison with the ATTO-labelled derivate.
References:
1 C. Haase, O. Seitz, Top.
Curr. Chem. 2007,
267, 1-36.
2 T. Maeda, S.-I. Nishimura, Chem. Eur. J. 2008, 14, 478-487.
3 G. K. Wagner, T. Pesnot, R. A. Field, Nat. Prod. Rep. 2009, 26, 1172-1194.
4 N. Lunau, Dissertation 2012,
University Hamburg.
5 S.
Wolf, R. M. Berrio, C. Meier , Eur. J.
Org. Chem. 2011, 6304-6313.
