title: Chiroptical properties of diamino carboxylic acids.
abstract: Diamino carboxylic acids have recently come to the attention of scientists working in the field of early life and its development. These are the monomers of a hypothetic early form of genetic material, the so-called Peptide Nucleic Acid (PNA) (Nielson et al., Proc Natl Acad Sci USA 2000;97:3868-3871). Since all biopolymers rely on a specific handedness of their building blocks, the question of symmetry breaking occurs in diamino acids and PNA in the same way as in amino acids and proteins. One possible mechanism for triggering this, is asymmetric photochemistry in interstellar/circumstellar matter by means of circularly polarized light (Bailey et al., Science 2005;281:672-674; Bailey, Orig Life Evol Biosphere 2001;21:167-183; Buschermöhle, Astrophys J 2005;624:821-826; Meierhenrich, Angew Chem Int Ed Engl 2005;44:5630-5634). Here we have measured the CD-spectra of four chiral diamino carboxylic acids, three of which were found in the Murchison meteorite (Meierhenrich, Proc Natl Acad Sci USA 2004;101:9182-9186). The spectra show a uniform peak at 200 nm. These results and additional quantum mechanical calculations of the involved molecular orbitals support the assumption that the process of symmetry breaking in diamino acids does not depend significantly on the length of the side chain. This means that one process alone could suffice to lead to symmetry breaking in all four measured diamino carboxylic acids and might even to some extent be transferable to monoamino acids, the monomers of proteins.
authors.affiliation: Institute for Applied and Physical Chemistry, University of Bremen, Leobener Strasse, 28359 Bremen, Germany. thoralf@uni-bremen.de
authors.forename: Jan Hendrik
authors.initials: JH
authors.lastname: Bredehöft
authors.forename: Katharina
authors.initials: K
authors.lastname: Breme
authors.forename: Uwe J
authors.initials: UJ
authors.lastname: Meierhenrich
authors.forename: Søren V
authors.initials: SV
authors.lastname: Hoffmann
authors.forename: Wolfram H-P
authors.initials: WH
authors.lastname: Thiemann
mesh_terms: D000599:Amino Acids, Diamino / Q000737:chemistry*; D000613:Aminobutyrates / Q000737:chemistry; D002264:Carboxylic Acids / Q000737:chemistry*; D002942:Circular Dichroism; D008239:Lysine / Q000737:chemistry; D019110:Meteoroids; D008958:Models, Molecular; D015394:Molecular Structure; D009952:Ornithine / Q000737:chemistry; D020135:Peptide Nucleic Acids / Q000737:chemistry; D055672:Static Electricity; D013237:Stereoisomerism; D015091:beta-Alanine / Q000031:analogs & derivatives / Q000737:chemistry
chemical_list: D000599:Amino Acids, Diamino; D000613:Aminobutyrates; D002264:Carboxylic Acids; D020135:Peptide Nucleic Acids; D015091:beta-Alanine; C005959:2,4-diaminobutyric acid; C011757:2,3-diaminopropionic acid; D009952:Ornithine; D008239:Lysine