N-glycans on the cell surface provide distinct
signatures that are recognized by different glycan-binding proteins
(GBPs) and pathogens. Most glycans in humans are asymmetric and isomeric,
yet their biological functions are not well understood due to their
lack of availability for studies. In this work, we have developed
an improved strategy for asymmetric N-glycan assembly
and diversification using designed common core substrates prepared
chemically for selective enzymatic fucosylation and sialylation. The
resulting 26 well-defined glycans that carry the sialic acid residue
on different antennae were used in a microarray as a representative
application to profile the binding specificity of hemagglutinin (HA)
from the avian influenza virus (H5N2). We found distinct binding affinity
for the Neu5Ac-Gal epitope linked to the N-acetylglucosamine
(GlcNAc) of different branches and only a minor effect in binding
for the terminal galactose on different branches. Overall, the microarray
analysis showed branch-biased and context-based recognition patterns.