Chiral peptide nucleic acids with a substituent in the N-(2-Aminoethy) glycine backbone

Molecules

Volumn 18, Issue 1, 2013, Pages 287-310

  Sugiyama, Toru ^a   Kittaka, Atsushi ^b  

^a UNIVERSITY OF TOKYO   (Japan)

^b TEIKYO UNIVERSITY   (Japan)

Author keywords

Antigene; Chiral; Peptide nucleic acid; Preorganization

Indexed keywords

EID: 84872847430     PISSN: None     EISSN: 14203049     Source Type: Journal    
DOI: 10.3390/molecules18010287     Document Type: Review

References (93)

1. Nielsen, P.E.; Egholm, M.; Berg, R.H.; Buchardt, O. Sequence-selective recognition of DNA by strand displacement with a thymine-substituted polyamide. Science 1991, 254, 1497-1500.
2. Egholm, M.; Buchardt, O.; Christensen, L.; Behrens, C.; Freier, S.M.; Driver, D.A.; Berg, R.H.; Kim, S.K.; Norden, B.; Nielsen, P.E. PNA hybridizes to complementary oligonucleotides obeying the Watson-Crick hydrogen-bonding rules. Nature 1993, 365, 566-568.
3. Jensen, K.K.; Orum, H.; Nielsen, P.E.; Norden, B. Kinetics for hybridization of peptide nucleic acids (PNA) with DNA and RNA studied with the BIAcore technique. Biochemistry 1997, 36, 5072-5077.
4. Ratilainen, T.; Holmen, A.; Tuite, E.; Nielsen, P.E.; Norden, B. Thermodynamics of sequencespecific binding of PNA to DNA. Biochemistry 2000, 39, 7781-7791.
5. Demidov, V.V.; Potaman, V.N.; Frank-Kamenetskii, M.D.; Egholm, M.; Buchardt, O.; Sonnichsen, S.H.; Nielsen, P.E. Stability of peptide nucleic acids in human serum and cellular extracts. Biochem. Pharmacol. 1994, 48, 1310-1313.
6. Hamilton, S.E.; Iyer, M.; Norton, J.C.; Corey, D.R. Specific and nonspecific inhibition of transcription by DNA, PNA, and phosphorothioate promoter analog duplexes. Bioorg. Med. Chem. Lett. 1996, 6, 2897-2900.
7. Cutrona, G.; Carpaneto, E.M.; Ulivi, M.; Roncella, S.; Landt, O.; Ferrarini, M.; Boffa, L.C. Effects in live cells of a c-myc anti-gene PNA linked to a nuclear localization signal. Nat. Biotechnol. 2000, 18, 300-303.
8. Boffa, L.C.; Cutrona, G.; Cilli, M.; Mati, S.; Damonte, G.; Mariani, M.R.; Millo, E.; Moroni, M.; Roncella, S.; Fedeli, F.; Ferrarini, M. Inhibition of Burkitt's lymphoma cells growth in SCID mice by a PNA specific for a regulatory sequence of the translocated c-myc. Cancer Gene Ther. 2007, 14, 220-226.
9. Tonelli, R.; Purgato, S.; Camerin, C.; Fronza, R.; Bologna, F.; Alboresi, S.; Franzoni, M.; Corradini, R.; Sforza, S.; Faccini, A.; Shohet, J.M.; Marchelli, R.; Pession, A. Antigene peptide nucleic acid specifically inhibits MYCN expression in human neuroblastoma cells leading to cell growth inhibition and apoptosis. Mol. Cancer Ther. 2005, 4, 779-786.
10. Cogoi, S.; Codognotto, A.; Rapozzi, V.; Meeuwenoord, N.; van der Marel, G.; Xodo, L.E. Transcription inhibition of oncogenic KRAS by a mutation-selective peptide nucleic acid conjugated to the PKKKRKV nuclear localization signal peptide. Biochemistry 2005, 44, 10510-10519.
11. Janowski, B.A.; Kaihatsu, K.; Huffman, K.E.; Schwartz, J.C.; Ram, R.; Hardy, D.; Mendelson, C.R.; Corey, D.R. Inhibiting transcription of chromosomal DNA with antigene peptide nucleic acids. Nat. Chem. Biol. 2005, 1, 210-215.
12. Kumar, V.A.; Ganesh, K.N. Conformationally constrained PNA analogues: Structural evolution toward DNA/RNA binding selectivity. Acc. Chem. Res. 2005, 38, 404-412.
13. Corradini, R.; Sforza, S.; Tedeschi, T.; Totsingan, F.; Manicardi, A.; Marchelli, R. Peptide nucleic acids with a structurally biased backbone. Updated review and emerging challenges. Curr. Top. Med. Chem. 2011, 11, 1535-1554.
14. Dueholm, K.L.; Petersen, K.H.; Jensen, D.K.; Egholm, M.; Nielsen, P.E.; Buchardt, O. Peptide nucleic acid (PNA) with a chiral backbone based on alanine. Bioorg. Med. Chem. Lett. 1994, 4, 1077-1080.
15. Haaima, G.; Lohse, A.; Buchardt, O.; Nielsen, P.E. Peptide nucleic acids (PNAs) containing thymine monomers derived from chiral amino acids: Hybridization and solubility properties of D-lysine PNA. Angew. Chem. Int. Ed. Engl. 1996, 35, 1939-1942.
16. Püschl, A.; Sforza, S.; Haaima, G.; Dahl, O.; Nielsen, P.E. Peptide nucleic acids (PNAs) with a functional backbone. Tetrahedron Lett. 1998, 39, 4707-4710.
17. Gupta, P.; Muse, O.; Rozners, E. Recognition of double-stranded RNA by guanidine-modified peptide nucleic acids. Biochemistry 2012, 51, 63-73.
18. Balaji, B.S.; Gallazzi, F.; Jia, F.; Lewis, M.R. An efficient, convenient solid-phase synthesis of amino acid-modified peptide nucleic acid monomers and oligomers. Bioconjug. Chem. 2006, 17, 551-558.
19. Corradini, R.; Sforza, S.; Dossena, A.; Palla, G.; Rocchi, R.; Filira, F.; Nastri, F.; Marchelli, R. Epimerization of peptide nucleic acids analogs during solid-phase synthesis: optimization of the coupling conditions for increasing the optical purity. J. Chem. Soc. Perkin Trans. 1 2001, 2690-2696.
20. Tedeschi, T.; Corradini, R.; Marchelli, R.; Pushl, A.; Nielsen, P.E. Racemization of chiral PNAs during solid-phase synthesis: Effect of the coupling conditions on enantiomeric purity. Tetrahedron: Asymmetry 2002, 13, 1629-1636.
21. Richter, L.S.; Zuckermann, R.N. Synthesis of peptide nucleic acids (PNA) by submonomer solid-phase synthesis. Bioorg. Med. Chem. Lett. 1995, 5, 1159-1163.
22. Viirre, R.D.; Hudson, R.H.E. Optimization of a solid-phase synthesis of a PNA monomer. Org. Lett. 2001, 3, 3931-3934.
23. Sforza, S.; Tedeschi, T.; Corradini, R.; Ciavardelli, D.; Dossena, A.; Marchelli, R. Fast, solid-phase synthesis of chiral peptide nucleic acids with a high optical purity by a submonomeric strategy. Eur. J. Org. Chem. 2003, 2003, 1056-1063.
24. Sforza, S.; Haaima, G.; Marchelli, R.; Nielsen, P.E. Chiral peptide nucleic acids (PNAs): Helix handedness and DNA recognition. Eur. J. Org. Chem. 1999, 1999, 197-204.
25. Sforza, S.; Corradini, R.; Ghirardi, S.; Dossena, A.; Marchelli, R. DNA binding of a D-lysinebased chiral PNA: Direction control and mismatch recognition. Eur. J. Org. Chem. 2000, 2000, 2905-2913.
26. Menchise, V.; de Simone, G.; Tedeschi, T.; Corradini, R.; Sforza, S.; Marchelli, R.; Capasso, D.; Saviano, M.; Pedone, C. Insights into peptide nucleic acid (PNA) structural features: The crystal structure of a D-lysine-based chiral PNA-DNA duplex. Proc. Natl. Acad. Sci. USA 2003, 100, 12021-12026.
27. Dose, C.; Seitz, O. Single nucleotide specific detection of DNA by native chemical ligation of fluorescence labeled PNA-probes. Bioorg. Med. Chem. 2008, 16, 65-77.
28. Zhou, P.; Dragulescu-Andrasi, A.; Bhattacharya, B.; O'Keefe, H.; Vatta, P.; Hyldig-Nielsen, J.J.; Ly, D.H. Synthesis of cell-permeable peptide nucleic acids and characterization of their hybridization and uptake properties. Bioorg. Med. Chem. Lett. 2006, 16, 4931-4935.
29. Rossi, S.; Calabretta, A.; Tedeschi, T.; Sforza, S.; Arcioni, S.; Baldoni, L.; Corradini, R.; Marchelli, R. Selective recognition of DNA from olive leaves and olive oil by PNA and modified-PNA microarrays. Artificial DNA PNA XNA 2012, 3, 63-72.
30. Hamzavi, R.; Dolle, F.; Tavitian, B.; Dahl, O.; Nielsen, P.E. Modulation of the pharmacokinetic properties of PNA: Preparation of galactosyl, mannosyl, fucosyl, N-Acetylgalactosaminyl, and N-Acetylglucosaminyl derivatives of aminoethylglycine peptide nucleic acid monomers and their incorporation into PNA oligomers. Bioconjug. Chem. 2003, 14, 941-954.
31. Hamzavi, R.; Meyer, C.; Metzler-Nolte, N. Synthesis of a C-linked glycosylated thymine-based PNA monomer and its incorporation into a PNA oligomer. Org. Biomol. Chem. 2005, 4, 3648-3651.
32. Aguado, G.P.; Rúa, F.; Branchadell, V.; Nielsen, P.E.; Ortuño, R.M. Cyclobutyl-carbonyl substituted PNA: Synthesis and study of a novel PNA derivative. Tetrahedron: Asymmetry 2006, 17, 2499-2503.
33. Dorn, S.; Aghaallaei, N.; Jung, G.; Bajoghli, B.; Werner, B.; Bock, H.; Lindhorst, T.; Czerny, T. Side chain modified peptide nucleic acids (PNA) for knock-down of six3 in medaka embryos. BMC Biotechnol. 2012, 12, doi:10.1186/1472-6750-12-50.
34. Dilek, I.; Madrid, M.; Singh, R.; Urrea, C.P.; Armitage, B.A. Effect of PNA backbone modifications on cyanine dye binding to PNA-DNA duplexes investigated by optical spectroscopy and molecular dynamics simulations. J. Am. Chem. Soc. 2005, 127, 3339-3345.
35. Gourishankar, A.; Ganesh, K.N. (a,a-dimethyl)glycyl (dmg) PNAs. Achiral PNA analogs that form stronger hybrids with cDNA relative to isosequential RNA. Artificial DNA PNA XNA 2012, 3, 5-13.
36. Lohse, J.; Dahl, O.; Nielsen, P.E. Double duplex invasion by peptide nucleic acid: A general principle for sequence-specific targeting of double-stranded DNA. Proc. Natl. Acad. Sci. USA 1999, 96, 11804-11808.
37. Ishizuka, T.; Yoshida, J.; Yamamoto, Y.; Sumaoka, J.; Tedeschi, T.; Corradini, R.; Sforza, S.; Komiyama, M. Chiral introduction of positive charges to PNA for double-duplex invasion to versatile sequences. Nucleic Acids Res. 2008, 36, 1464-1471.
38. Koppelhus, U.; Nielsen, P.E. Cellular delivery of peptide nucleic acid (PNA). Adv. Drug Deliv. Rev. 2003, 55, 267-280.
39. Nielsen, P.E. Addressing the challenges of cellular delivery and bioavailability of peptide nucleic acids (PNA). Q. Rev. Biophys. 2005, 38, 345-350.
40. Shiraishi, T.; Pankratova, S.; Nielsen, P.E. Calcium ions effectively enhance the effect of antisense peptide nucleic acids conjugated to cationic Tat and oligoarginine Peptides. Chem. Biol. 2005, 12, 923-929.
41. Hu, J.; Corey, D.R. Inhibiting gene expression with peptide nucleic acid (PNA)-peptide conjugates that target chromosomal DNA. Biochemistry 2007, 46, 7581-7589.
42. Koppelhus, U.; Awasthi, S.K.; Zachar, V.; Holst, H.U.; Ebbesen, P.; Nielsen, P.E. Cell-dependent differential cellular uptake of PNA, peptides, and PNA-peptide conjugates. Antisense Nucleic Acid Drug Dev. 2002, 12, 51-63.
43. Zhou, P.; Wang, M.; Du, L.; Fisher, G.W.; Waggoner, A.; Ly, D.H. Novel binding and efficient cellular uptake of guanidine-based peptide nucleic acids (GPNA). J. Am. Chem. Soc. 2003, 125, 6878-6879.
44. Nagahara, H.; Vocero-Akbini, A.M.; Snyder, E.L.; Ho, A.; Latham, D.G.; Lissy, N.A.; Becker-Hapak, M.; Ezhevsky, S.; Dowdy, S.F. Transduction of full-length TAT fusion proteins into mammalian cells: TAT-p27Kip1 induces cell migration. Nat. Med. 1998, 4, 1449-1452.
45. Futaki, S.; Suzuki, T.; Ohashi, W.; Yagami, T.; Tanaka, S.; Ueda, K.; Sugiura, Y. Arginine-rich peptides. J. Biol. Chem. 2001, 276, 5836-5840.
46. Wender, P.A.; Mitchell, D.J.; Pattabiraman, K.; Pelkey, E.T.; Steinman, L.; Rothbard, J.B. The design, synthesis, and evaluation of molecules that enable or enhance cellular uptake: Peptoid molecular transporters. Proc. Natl. Acad. Sci. USA 2000, 97, 13003-13008.
47. Dragulescu-Andrasi, A.; Zhou, P.; He, G.; Ly, D.H. Cell-permeable GPNA with appropriate backbone stereochemistry and spacing binds sequence- specifically to RNA. Chem. Commun. 2005, 41, 244-246.
48. Rothbard, J.B.; Jessop, T.C.; Lewis, R.S.; Murray, B.A.; Wender, P.A. Role of membrane potential and hydrogen bonding in the mechanism of translocation of guanidinium-rich peptides into cells. J. Am. Chem. Soc. 2004, 126, 9506-9507.
49. Dragulescu-Andrasi, A.; Rapireddy, S.; He, G.; Bhattacharya, B.; Hyldig-Nielsen, J.J.; Zon, G.; Ly, D.H. Cell-permeable peptide nucleic acid designed to bind to the 5'-untranslated region of E-cadherin transcript induces potent and sequence-specific antisense effects. J. Am. Chem. Soc. 2006, 128, 16104-16112.
50. Doyle, D.F.; Braasch, D.A.; Simmons, C.G.; Janowski, B.A.; Corey, D.R. Inhibition of gene expression inside cells by peptide nucleic acids: effect of mRNA target sequence, mismatched bases, and PNA length. Biochemistry 2001, 40, 53-64.
51. Kosynkina, L.; Wang, W.; Liang, T.C. A Convenient synthesis of chiral peptide nucleic acid (PNA) monomers. Tetrahedron Lett. 1994, 35, 5173-5176.
52. Tedeschi, T.; Sforza, S.; Corradini, R.; Marchelli, R. Synthesis of new chiral PNAs bearing a dipeptide-mimic monomer with two lysine-derived stereogenic centres. Tetrahedron Lett. 2005, 46, 8395-8399.
53. Englund, E.A.; Appella, D.H. Synthesis of -substituted peptide nucleic acids: A new place to attach fluorophores without affecting DNA binding. Org. Lett. 2005, 7, 3465-3467.
54. Dose, C.; Seitz, O. Convergent Synthesis of Peptide Nucleic Acids by Native Chemical Ligation. Org. Lett. 2005, 7, 4365-4368.
55. Ficht, S.; Dose, C.; Seitz, O. As fast and selective as enzymatic ligations: Unpaired nucleobases increase the selectivity of DNA-controlled native chemical PNA ligation. ChemBioChem 2005, 6, 2098-2103.
56. Stanfield, C.F.; Parker, J.E.; Kanellis, P. Preparation of protected amino aldehydes. J. Org. Chem. 1981, 46, 4797-4798.
57. Rittle, K.E.; Homnick, C.F.; Ponticello, G.S.; Evans, B.E. A synthesis of statine utilizing an oxidative route to chiral a-Amino aldehydes. J. Org. Chem. 1982, 47, 3016-3018.
58. Dragulescu-Andrasi, A.; Rapireddy, S.; Frezza, B.M.; Gayathri, C.; Gil, R.R.; Ly, D.H. A simple -backbone modification preorganizes peptide nucleic acid into a helical structure. J. Am. Chem. Soc. 2006, 128, 10258-10267.
59. De Koning, M.C.; Petersen, L.; Weterings, J.J.; Overhand, M.; van der Marel, G.A.; Filippov, D.V. Synthesis of thiol-modified peptide nucleic acids designed for post-Assembly conjugation reactions. Tetrahedron 2006, 62, 3248-3258.
60. Sahu, B.; Chenna, V.; Lathrop, K.L.; Thomas, S.M.; Zon, G.; Livak, K.J.; Ly, D.H. Synthesis of conformationally preorganized and cell-permeable guanidine-based -peptide nucleic acids (-GPNAs). J. Org. Chem. 2009, 74, 1509-1516.
61. Sahu, B.; Sacui, I.; Rapireddy, S.; Zanotti, K.J.; Bahal, R.; Armitage, B.A.; Ly, D.H. Synthesis and characterization of conformationally preorganized, (R)-diethylene glycol-containing -peptide nucleic acids with superior hybridization properties and water solubility. J. Org. Chem. 2011, 76, 5614-5627.
62. Falkiewicz, B.; Kolodziejczyk, A.S.; Liberek, B.; Wisniewski, K. Synthesis of achiral and chiral peptide nucleic acid (PNA) monomers using Mitsunobu reaction. Tetrahedron 2001, 57, 7909-7917.
63. Chouikhi, D.; Ciobanu, M.; Zambaldo, C.; Duplan, V.; Barluenga, S.; Winssinger, N. Expanding the scope of PNA-encoded synthesis (PES): Mtt-protected PNA fully orthogonal to fmoc chemistry and a broad array of robust diversity-generating reactions. Chem. Eur. J. 2012, 18, 12698-12704.
64. Englund, E.A.; Appella, D.H. -Substituted peptide nucleic acids constructed from L-lysine are a versatile scaffold for multifunctional display. Angew. Chem. Int. Ed. 2007, 46, 1414-1418.
65. Englund, E.A.; Wang, D.; Fujigaki, H.; Sakai, H.; Micklitsch, C.M.; Ghirlando, R.; Martin-Manso, G.; Pendrak, M.L.; Roberts, D.D.; Durell, S.R.; et al. Programmable multivalent display of receptor ligands using peptide nucleic acid nanoscaffolds. Nat. Commun. 2012, doi:10.1038/ncomms1629.
66. Scheibe, C.; Bujotzek, A.; Dernedde, J.; Weberb, M.; Seitz, O. DNA-programmed spatial screening of carbohydrate-lectin interactions. Chem. Sci. 2011, 2, 770-775.
67. Sforza, S.; Tedeschi, T.; Corradini, R.; Marchelli, R. Induction of helical handedness and DNA binding properties of peptide nucleic acids (PNAs) with two stereogenic centres. Eur. J. Org. Chem. 2007, 2007, 5879-5885.
68. Avitabile, C.; Moggio, L.; Malgieri, G.; Capasso, D.; Gaetano, S.D.; Saviano, M.; Pedone, C.; Romanelli, A. - sulphate PNA (PNA S): Highly selective DNA binding molecule showing promising antigene activity. PLoS One 2012, 7, e35774.
69. Yeh, J.I.; Boris Shivachev, B.; Rapireddy, S.; Crawford, M.J.; Gil, R.R.; Du, S.; Madrid, M.; Ly, D.H. Crystal structure of chiral -PNA with complementary DNA strand: Insights into the stability and specificity of recognition and conformational preorganization. J. Am. Chem. Soc. 2010, 132, 10717-10727.
70. Crawford, M.J.; Rapireddy, S.; Bahal, R.; Sacui, I.; Ly, D.H. Effect of steric constraint at the -backbone position on the conformations and hybridization properties of PNAs. J. Nucleic Acids 2011, 2011, doi:10.4061/2011/652702.
71. Nielsen, P.E.; Christensen, L. Strand displacement binding of a duplex-forming homopurine PNA to a homopyrimidine duplex DNA target. J. Am. Chem. Soc. 1996, 118, 2287-2288.
72. Zhang, X.; Ishihra, T.; Corey, D.R. Strand invasion by mixed base PNAs and a PNA-peptide chimera. Nucleic Acids Res. 2000, 28, 3332-3338.
73. Smolina, I.V.; Demidov, V.V.; Soldatenkov1, V.A.; Chasovskikh1, S.G.; Frank-Kamenetskii, M.D. End invasion of peptide nucleic acids (PNAs) with mixed-base composition into linear DNA duplexes. Nucleic Acids Res. 2005, 33, e146.
74. Avitabile, C.; Saviano, M.; D'Andrea, L.D.; Bianchi, N.; Fabbri, E.; Brognara, E.; Gambari, R.; Romanelli, A. Targeting pre-miRNA by peptide nucleic acids. Artificial DNA PNA XNA 2012, 3, 88-96.
75. Rapireddy, S.; He, G.; Roy, S.; Armitage, B.A.; Ly, D.H. Strand invasion of mixed-sequence B-DNA by acridine-linked, -peptide nucleic acid (-PNA). J. Am. Chem. Soc. 2007, 129, 15596-15600.
76. Chenna, V.; Rapireddy, S.; Sahu, B.; Ausin, C.; Pedroso, E.; Ly, D.H. A simple cytosine to G-clamp nucleobase substitution enables chiral -PNAs to invade mixed-sequence double-helical B-form DNA. ChemBioChem 2008, 9, 2388-2391.
77. Rapireddy, S.; Bahal, R.; Ly, D.H. Strand invasion of mixed-sequence, double-helical B-DNA by -peptide nucleic acids containing G-clamp nucleobases under physiological conditions. Biochemistry 2011, 50, 3913-3918.
78. He, G.; Rapireddy, S.; Bahal, R.; Sahu, B.; Ly, D.H. Strand invasion of extended, mixed-sequence B-DNA by -PNAs. J. Am. Chem. Soc. 2009, 131, 12088-12090.
79. Bahal, R.; Sahu, B.; Rapireddy, S.; Lee, C.-M.; Ly, D.H. Sequence-unrestricted, Watson-Crick recognition of double helical B-DNA by (R)-MiniPEG-PNAs. ChemBioChem 2012, 13, 56-60.
80. Manicardi, A.; Fabbri, E.; Tedeschi, T.; Sforza, S.; Nicoletta Bianchi, N.; Brognara, E.; Gambari, R.; Marchelli, R.; Corradini, R. Cellular uptakes, biostabilities and anti-miR-210 activities of chiral arginine-PNAs in leukaemic K562 cells. ChemBioChem 2012, 13, 1327-1337.
81. Manizardi, A.; Calabretta, A.; Bencivenni, M.; Tedeschi, T.; Sforza, S.; Corradini, R.; Marchelli, R. Affinity and selectivity of C2- and C5-substituted "chiral-box" PNA in solution and on microarrays. Chirality 2010, 22, E161-E171.
82. Sforza, S.; Tedeschi, T.; Calabretta, A.; Corradini, R.; Camerin, C.; Tonelli, R.; Pession, A.; Marchelli, R. A peptide nucleic acid embedding a pseudopeptide nuclear localization sequence in the backbone behaves as a peptide mimic. Eur. J. Org. Chem. 2010, 2010, 2441-2444.
83. Mitra, R.; Ganesh, K.N. PNAs grafted with (a/-, R/S)-Aminomethylene pendants: Regio and stereo specific effects on DNA binding and improved cell uptake. Chem. Commun. 2011, 47, 1198-1200.
84. Mitra, R.; Ganesh, K.N. Aminomethylene peptide nucleic acid (am-PNA): Synthesis, regio- /stereospecific DNA binding, and differential cell uptake of (a/-,R/S)am-PNA analogues. J. Org. Chem. 2012, 77, 5696-5704.
85. Myers, M.C.; Witschi, M.A.; Larionova, N.V.; Frank, J.M.; Haynes, R.D.; Hara, T.; Grajkowski, A.; Appella, D.H. A cyclopentane conformational restraint for a peptide nucleic acid: Design, asymmetric synthesis, and improved binding affinity to DNA and RNA. Org. Lett. 2003, 5, 2695-2698.
86. Pokorski, J.K.; Witschi, M.A.; Purnell, B.L.; Appella, D.H. (S,S)-trans-Cyclopentane-constrained peptide nucleic acids. A general backbone modification that improves binding affinity and sequence specificity. J. Am. Chem. Soc. 2004, 126, 15067-15073.
87. Pokorski, J.K.; Myers, M.C.; Appella, D.H. Cyclopropane PNA: Observable triplex melting in a PNA constrained with a 3-membered ring. Tetrahedron Lett. 2005, 46, 915-917.
88. Govindaraju, T.; Kumar, V.A.; Ganesh, K.N. cis-Cyclopentyl PNA (cpPNA) as constrained chiral PNA analogues: Stereochemical dependence of DNA/RNA hybridiation. Chem. Commun. 2004, 860-861.
89. Govindaraju, T.; Kumar, V.A.; Ganesh, K.N. (SR/RS)-Cyclohexanyl PNAs: Conformationally preorganized PNA analogues with unprecedented preference for duplex formation with RNA. J. Am. Chem. Soc. 2005, 127, 4144-4145.
90. Lagriffoule, P.; Wittung, P.; Ericksson, M.; Jensen, D.K.; Norden, B.; Buchardt, O.; Nielsen, P.E. Peptide nucleic acids with a conformationally constrained chiral cyclohexyl-derived backbone. Chem. Eur. J. 1997, 3, 912-919.
91. Bregant, S.; Burlina, F.; Vaissermann, J.; Chassaing, G. Synthesis and hybridization properties of thiazolidine PNAs. Eur. J. Org. Chem. 2001, 2001, 3285-3294.
92. Bregant, S.; Burlina, F.; Chassaing, G. New thiazane and thiazolidine PNA monomers: Synthesis, incorporation into PNAs and hybridization studies. Bioorg. Med. Chem. Lett. 2002, 12, 1047-1050.
93. Sugiyama, T.; Imamura, Y.; Demizu, Y.; Kurihara, M.; Takano, M.; Kittaka, A. ß-PNA: Peptide nucleic acid (PNA) with a chiral center at the ß-position of the PNA backbone. Bioorg. Med. Chem. Lett. 2011, 21, 7317-7320.