Threose nucleic acid
(TNA) is a polymer
similar to DNA
but differing in the composition of its "backbone". TNA is not known to occur in existing life on Earth.
DNA and RNA have a deoxyribose and ribose sugar backbone, respectively, whereas TNA's backbone is composed of repeating threose units linked by phosphodiester bonds. The threose molecule is easier to assemble than ribose making it a possible precursor to RNA.
DNA-TNA hybrid chains have been made in the laboratory using DNA polymerase.
TNA can specifically base pair with RNA and DNA; this capability and chemical simplicity suggests that TNA could have preceded RNA as genetic material.
- Orgel, Leslie (2000). "A Simpler Nucleic Acid". Science 290 (5495): 1306–1307.
- Watt, Gregory (2005). "Modified nucleic acids on display". Nature Chemical Biology
- Schoning, K; Scholz P; Guntha S; Wu X; Krishnamurthy R; Eschenmoser A (2000). "Chemical etiology of nucleic acid structure: the alpha-threofuranosyl-(3'->2') oligonucleotide system.". Science