Chiral discrimination of α‐amino acids by DNA tetranucleotides under electrospray ionization conditions

A set of DNA tetranucleotides, which are 3′- or 5′-end extended versions of GCA, was used as chiral selectors for the discrimination of enantiomers of α-amino acids. The [X+Y–2H]2− ions of the 1:1 complexes were generated by electrospraying a mixture of tetranucleotide (X) and amino acid (Y) solution. Chiral discrimination was achieved by studying the collision-induced dissociation spectra of the [X+Y–2H]2− ion and the ratio of relative abundance of precursor ion to that of the product ion was used to measure the extent of discrimination. Among the tetranucleotides used, GCAA and GGCA exhibited better discrimination, in which GCAA showed D-selectivity and GGCA showed L-selectivity for the studied amino acids. In addition, binding constants were measured for the 1:1 complexes of phenylalanine enantiomers with GCAA and GGCA. Copyright © 2007 John Wiley & Sons, Ltd.