文摘
We report the chiroptical properties and lectin affinities of poly(phenylacetylene)s featuringsaccharide functionalities including D-glucopyranoside and D-galactopyranoside. The glycoconjugated poly(phenylacetylene)s were synthesized by rhodium mediated polymerization from phenylacetylene monomerscontaining a series of saccharide groups; 4-ethynylphenyl 2,3,4,6-tetra-O-acetyl--D-glucopyranoside (PA--Glc-OAc), -D-glucopyranoside (PA--Glc-OAc), -D-galactopyranoside (PA--Gal-OAc), and -D-galactopyranoside (PA--Gal-OAc). On the basis of CD and UV-vis experiments, these polymers were found to havebiased helical conformations in a variety of solvents, such as CHCl3, THF, and HFIP. The deprotection of theacetyl groups using CH3ONa provided the linear saccharide arrays with diverse saccharide functionalities; poly-PA--Glc, poly-PA--Glc, poly-PA--Gal, and poly-PA--Gal. CD experiments revealed that poly-PA--Glcand poly-PA--Glc have identical helical structures, and poly-PA--Gal and poly-PA--Gal feature mirror-imaged helical structures. The binding affinities to lectins were demonstrated by a fluorometric assay using thefluorescein isothiocyanate labeled lectins, such as Concanavalin A (FITC-Con A) and peanut agglutinin (FITC-PNA). As expected, increasingly enhanced affinities for Con A and PNA were observed for the helical saccharidearrays in comparison to the monomeric models. Accordingly, the enhanced affinities are essentially correlatedwith the multivalency and conformational organization of the saccharide functionalities in the arrays.
