title: Synthesis and characterization of 2'-modified-4'-thioRNA: a comprehensive comparison of nuclease stability.
abstract: We report herein the synthesis and physical and physiological characterization of fully modified 2'-modified-4'-thioRNAs, i.e. 2'-fluoro-4'-thioRNA (F-SRNA) and 2'-O-Me-4'-thioRNA (Me-SRNA), which can be considered as a hybrid chemical modification based on 2'-modified oligonucleotides (ONs) and 4'-thioRNA (SRNA). In its hybridization with a complementary RNA, F-SRNA (15mer) showed the highest T(m) value (+16 degrees C relative to the natural RNA duplex). In addition, both F-SRNA and Me-SRNA preferred RNA as a complementary partner rather than DNA in duplex formation. The results of a comprehensive comparison of nuclease stability of single-stranded F-SRNA and Me-SRNA along with 2'-fluoroRNA (FRNA), 2'-O-MeRNA (MeRNA), SRNA, and natural RNA and DNA, revealed that Me-SRNA had the highest stability with t(1/2) values of > 24 h against S1 nuclease (an endonuclease) and 79.2 min against SVPD (a 3'-exonuclease). Moreover, the stability of Me-SRNA was significantly improved in 50% human plasma (t(1/2) = 1631 min) compared with FRNA (t(1/2) = 53.2 min) and MeRNA (t(1/2) = 187 min), whose modifications are currently used as components of therapeutic aptamers. The results presented in this article will, it is hoped, contribute to the development of 2'-modified-4'-thioRNAs, especially Me-SRNA, as a new RNA molecule for therapeutic applications.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita-12, Nishi-6, Kita-ku, Sapporo 060-0812, Japan.
authors.forename: Mayumi
authors.initials: M
authors.lastname: Takahashi
authors.forename: Noriaki
authors.initials: N
authors.lastname: Minakawa
authors.forename: Akira
authors.initials: A
authors.lastname: Matsuda
mesh_terms: D004247:DNA / Q000737:chemistry; D005656:Fungal Proteins / Q000378:metabolism; D006801:Humans; D009691:Nucleic Acid Denaturation; D009693:Nucleic Acid Hybridization; D009843:Oligoribonucleotides / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D043264:Phosphodiesterase I / Q000378:metabolism; D012313:RNA / Q000737:chemistry; D012260:Ribonucleases / Q000097:blood / Q000378:metabolism*; D015719:Single-Strand Specific DNA and RNA Endonucleases / Q000378:metabolism; D013873:Thionucleotides / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; D009843:Oligoribonucleotides; D013873:Thionucleotides; D012313:RNA; D004247:DNA; D012260:Ribonucleases; C526098:Endonuclease S1, Aspergillus; D015719:Single-Strand Specific DNA and RNA Endonucleases; D043264:Phosphodiesterase I; C470790:phosphodiesterase I, snake venom