Comb-like poly-N-substituted glycines as monodisperse drag-tags for free-solution DNA sequencing by capillary electrophoresis

ORGN 131

Russell D Haynes, r-haynes@northwestern.edu1, Robert J Meagher, rjmeagher@northwestern.edu2, Jennifer Coyne, j-coyne@northwestern.edu3, and Annelise E. Barron, a-barron@northwestern.edu3. (1) Department of Chemistry, Northwestern University, 2145 N Sheridan Rd, Evanston, IL 60208, (2) Sandia National Laboratories, PO Box 969, Livermore, CA 94551, (3) Department of Chemical and Biological Engineering, Northwestern University, 2145 N Sheridan Rd, Evanston, IL 60208
DNA sequencing is typically done by capillary array electrophoresis with the use of highly viscous polymer solutions ("gels") to separate DNA molecules according to size with single-base resolution. We demonstrate DNA sequencing by a different approach not requiring a gel, in which DNA molecules are tagged with monodisperse, water-soluble polypeptoids that enable free-solution capillary electrophoretic separation. For this purpose, we synthesized a novel class of branched, comb-like poly-N-substituted glycine drag-tags and attached them to DNA primers via a thiol-maleimide linkage. A linear, 30mer polypeptoid backbone with hydrophilic N-methoxyethyl (NMEG) side chains interspersed with reactive amino groups was synthesized by SPPS, HPLC-purified, and then derivatized via peptide bond formation with shorter, monodisperse oligoNMEGs to form monodisperse, comb-like conjugates. These drag-tags provide excellent DNA sequencing by free-solution capillary electrophoresis, up to about 100 bases. This family of branched drag-tags provides high frictional drag, even on a relatively short backbone.