Studies of Highly-Ordered
Heterodiantennary Mannose/Glucose-Functionalized
Polymers and Concanavalin A Protein Interactions Using Isothermal
Titration Calorimetry
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Abstract
Preparations of the highly ordered
monoantennary, homofunctional
diantennary, and heterofunctional diantennary neoglycopolymers of
α-d-mannose and β-d-glucose residues
were achieved via ring-opening metathesis polymerization. Isothermal
titration calorimetry measurements of these synthetic neoglycopolymers
with Concanavalin A (Con A), revealed that heterofunctional diantennary
architectures bearing both α-mannose and nonbinding β-glucose
units, poly(Man-Glc), binds to Con A (<i>K</i><sub>a</sub> = 16.1 × 10<sup>6</sup> M<sup>–1</sup>) comparably to
homofunctional diantennary neoglycopolymer (<i>K</i><sub>a</sub> = 30 × 10<sup>6</sup> M<sup>–1</sup>) bearing
only α-mannose unit, poly(Man-Man). In addition, poly(Man-Glc)
neoglycopolymer shows a nearly 5-fold increasing in binding affinity
compared to monoantennary neoglycopolymer, poly(Man). Although the
exact mechanism for the high binding affinity of poly(Man-Glc) to
Con A is unclear, we hypothesize that the α-mannose bound to
Con A might facilitate interaction of β-glucose with the extended
binding site of Con A due to the close proximity of β-glucose
to α-mannose residues in the designed polymerizable scaffold