3c1p

Publication Abstract from PubMed

The crystal structure of the PNA (peptide nucleic acid) oligomer H-Lys-HalG-AlaG-HalC-AlaG-HalC-AlaC-Lys-NH(2) (PNA1, amino acids with D-configuration are underlined, Ala = alanyl, Hal = homoalanyl) has been determined by ab initio direct methods and refined against 1.0 A data. The asymmetric unit consists of a tetrameric cage with almost ideal Watson-Crick C-G base pairing of all the guanine and cytosine side-chain substituents. Each PNA strand has a 90 degrees beta-turn every second residue, stabilized by three hydrogen bonds between the backbone amides. The first, second, fifth and sixth bases stack on one side of the monomer and pair with the corresponding complementary bases of a second monomer to form a dimer. The two remaining bases on each side of the resulting dimer form Watson-Crick pairs with the complementary bases of a second dimer, leading to a unique cage structure. The extra methylene groups in the homoalanyl residues enable stacking of the bases with an optimal distance between base-planes but also with an appreciable lateral displacement (slide).

Continuous beta-turn fold of an alternating alanyl/homoalanyl peptide nucleic acid.,Cuesta-Seijo JA, Zhang J, Diederichsen U, Sheldrick GM Acta Crystallogr D Biol Crystallogr. 2012 Aug;68(Pt 8):1067-70. Epub 2012 Jul 17. PMID:22868773^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.