Synthesis and Characterization of Polyacrylamides Containing Nucleic Acid Base Pendants as Polynucleotide Analogs (Grafting, Diamino).

A new type of polymer species, polyacrylamide possessing an amino group at the terminus of the branched chain as the site for nucleic acid base grafting, has been synthesized. This type of polyacrylamide could provide the polynucleotide analogs with a substantial spacing distance between the nucleic acid base and the polymer backbone. An objective of this research was to examine how this spacing distance effects the conformational order of the polymer. In order to have a better underst and ing of the effect of bond rigidity on the degree of base stacking, both the amide and amine bonds were used to attach the pendants onto the amino active site. A chiral center was generated on the branch of the polyacrylamide to allow conformational studies using circular dichroism. The characterization of poly(2-amino-2-methylpropyl)-acrylamide and optically active poly(2-amino-2-methylbutyl)acrylamide using vapor phase osmometry, gel permeation chromatography, and dilute solution viscometry indicated that these polymeric materials possessed polyelectrolyte-type properties. The wide range of softening points was observed for these polymers suggesting that their branched chain prevents them from crystallizing. The nucleic acid base grafted polyacrylamides, prepared by polymer-analogous reactions, have 70-75% grafting efficiency in the case of the adenine base and 45-90% in the case of the uracil base. A modified procedure was introduced and provided a 100% of the nucleic acid bases as side chain pendants. Hypochromic effects were observed in the absorbance spectra of the nucleic acid base grafted polyacrylamides. The stacking interaction was found to be effected by both the electrostatic repulsion between charged bases and the spacing distance between the pendant group and the main chain. Increase in grafting efficiency resulted in an increase in percent hypochromicity. Continuous mixing experiments involving the synthetic polyacrylamides with complementary bases suggested that polymer-polymer mixtures form base-paired complexes only in neutral aqueous solution. The collective information from NMR, UV, and CD methods suggested that poly(2-amino-2-methylpropyl)acrylamide grafted with adenine base contains some local order. On the other h and , poly(2-amino-2-methylbutyl)acrylamide grafted with either adenine or uracil bases exist in somewhat less ordered conformations.Ph.D.Polymer chemistryUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/160308/1/8502810.pd