Synthesis of neoglycoconjugates containing deaminated neuraminic acid (KDN) using rat liver alpha2,6-sialyltransferase |
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Authors: | Angata T; Matsuda T; Kitajima K |
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Institution: | Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, Japan. |
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Abstract: | 2-Keto-3-deoxy-D- glycero -D- galacto -nononic acid (KDN) was introduced
into asialotransferrin and N -acetyllactosamine (LacNAc) from CMP-KDN by
using rat liver Galbeta1-->4GlcNAc alpha2, 6- sialyltransferase to form
KDN-transferrin and KDN-LacNAc. These structures contain terminal
KDNalpha2-->6Gal-residues, a glycotope that has not yet been described
in natural glycoconjugates. KDN was transferred to all four Gal residues in
asialotransferrin by this enzyme. The incorporation efficiency of KDN from
CMP-KDN into asialotransferrin was about half that of Neu5Ac from
CMP-Neu5Ac, based on the V max/ K m values for these donor substrates,
0.0527 min-1and 0.119 min-1, respectively. The KDNalpha2-->6Gal linkage
was resistant to exosialidase treatment, in contrast to the sensitivity of
the Neu5Acalpha2-->6Gal linkage. Interestingly, Sambucus sieboldiana
agglutinin (SSA) was shown to prefer KDN-transferrin to the corresponding
Neu5Ac-transferrin, as estimated by slot-blot analysis. The use of an
alpha2,6-sialyltransferase to synthesize neoglycoproteins containing KDN
has not been previously reported. Their facile synthesis using CMP-KDN and
sialyltransferases with different specificities offers new possibilities to
study the function of neo-KDN- glycoconjugates, and to explore their use in
glycotechnology.
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