Functionalized DNA: A New Replicable Biopolymer We thank Dr. Andreas Marx, University of Bonn, for helpful advice and discussions. This work was supported by the Fonds der Chemischen Industrie, the Karl-Ziegler Stiftung, and the Deutsche Forschungsgemeinschaft.

New DNA: By enzymatic polymerization of base-modified nucleoside triphosphates, a functionalized DNA (fDNA; see picture) was generated in which every base bears an additional amino acid like residue, thus mimicking the functional group repertoire of peptides on a nucleic acid backbone. These modified oligonucleotides can in turn serve as templates for polymerase chain reaction amplification, thus utilizing fDNA as a novel class of biopolymers for in vitro selection techniques.