SYNTHESIS AND CHARACTERIZATION OF POLYMER-(MULTI)-PEPTIDE CONJUGATES FOR CONTROL OF SPECIFIC CELL-AGGREGATION

A new synthetic approach has been applied to obtain novel di-, tetra-, and (multi)-peptide containing polymer conjugates in quantitative yie lds with a high degree of conjugation. Bis-(N-hydroxysuccinimidyl) est ers of PEG (M-w = 200, 600, 1400, 2000, and 3400) were synthesized and studied in a condensation reaction with synthetic peptides: glycine-g lycine-tyrosine-arginine (GGYR), a model peptide, and glycine-arginine -glycine-aspartic acid-tyrosine (GRGDY), a sequence known to promote c ell adhesion and aggregation Tetra-substituted derivatives of PEG-base d conjugates were synthesized by coupling L-aspartic acid and L-aspart yl-L-phenylalanine through a condensation procedure in organic media. Poly(acrylic acid) and co-polymers (M-w = 2000 and 5000) were studied as a model of multifunctional linear polymers in the reaction with L-t ryptophan and GGYR. Alternative polymer-(multi)peptide conjugates were successfully synthesized using Starburst(R) dendrimer PAMAM (G = 3), 'short' and 'long'-chain PEG-based active esters and GRGDY. The struct ure of the intermediate precursors and peptide-conjugates was confirme d by spectral (UV-Vis, FTIR, H-1-NMR) and chromatographic (RP-KPLC and SEC) methods. By varying the properties of the interconnecting polyme r -- such as hydrophobicity, molecular weight, and functionality -- a set of polymer-GRGDY conjugates was synthesized.