3 research outputs found
Studies of Highly-Ordered Heterodiantennary Mannose/Glucose-Functionalized Polymers and Concanavalin A Protein Interactions Using Isothermal Titration Calorimetry
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, polyÂ(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, polyÂ(Man-Man). In addition, polyÂ(Man-Glc)
neoglycopolymer shows a nearly 5-fold increasing in binding affinity
compared to monoantennary neoglycopolymer, polyÂ(Man). Although the
exact mechanism for the high binding affinity of polyÂ(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
Glycoform Remodeling Generates a Synthetic T Cell Phenotype
The
glycan of specific proteins can dictate the response of cells to stimuli,
and thus their phenotype. We describe a chemical strategy to modify
the cellular glycoform of T cells, which resulted in a modified cellular
response. Our data indicate that chemical modification of the phosphatase
CD45 is responsible for the observed differences in response to receptor
cross-linking. By increasing the content of galactose epitopes in
the glycocalyx of a lymphoma cell line, we were able to increase the
response of the cell to lectin stimulation through the glycoprotein
receptor, CD45. The method described here exploits metabolic labeling
of a cell to reprogram the cellular response to external stimuli though
changes in the number of lectin binding sites on the cell surface
Glycosidase Inhibition by Multivalent Presentation of Heparan Sulfate Saccharides on Bottlebrush Polymers
We
report herein the first-time exploration of the attachment of
well-defined saccharide units onto a synthetic polymer backbone for
the inhibition of a glycosidase. More specifically, glycopolymers
endowed with heparan sulfate (HS) disaccharides were established to
inhibit the glycosidase, heparanase, with an IC<sub>50</sub> value
in the low nanomolar range (1.05 ± 0.02 nm), a thousand-fold
amplification over its monovalent counterpart. The monomeric moieties
of these glycopolymers were designed in silico to manipulate the well-established
glycotope of heparanase into an inhitope. Studies concluded that (1)
the glycopolymers are hydrolytic stable toward heparanase, (2) longer
polymer length provides greater inhibition, and (3) increased local
saccharide density (monoantennary vs diantennary) is negligible due
to hindered active site of heparanase. Furthermore, HS oligosaccharide
and polysaccharide controls illustrate the enhanced potency of a multivalent
scaffold. Overall, the results on these studies of the multivalent
presentation of saccharides on bottlebrush polymers serve as the platform
for the design of potent glycosidase inhibitors and have potential
to be applied to other HS-degrading proteins