Kinetics and Mechanism of Facile and Selective Dephosphorylation of 2‘-Phosphorylated and 2‘-Thiophosphorylated Dinucleotides: Neighboring 3‘−5‘ Phosphodiester Promotes 2‘-Dephosphorylation
摘要:
2'-phosphorylated and 2'-thiophosphorylated dinucleotides U(2'-p)pU (1) and U(2'-ps)pU (2) were found to undergo facile 2'-specific dephosphorylation at 90 degrees C in neutral aqueous solution to give UpU, and the first-order rate constants of these reactions were determined by HPLC. Particularly, U(2'-ps)pU (2, k = 1.38 +/- 0.4 x 10(-3) s(-1), t(comp) = 1 h) was cleanly dephosphorylated ca. 100 times more rapidly than U(2'-p)pU (1, k = 1.41 +/- 0.05 x 10(-5) s(-1), t(comp) = 72 h). Dephosphorylations of 1 and 2 were faster than those of thymidine 3'-phosphate (8) and thymidine 3'-thiophosphate (9), respectively. The kinetic data observed were independent of the 2'- or 3'-position of the phosphate group and the kind of base moiety. The neighboring 3'-5' phosphodiester function most probably promotes the 2'-dephosphorylation efficiently. A branched trimer, U(2'-pU)pU (3), and related compounds having a substituent on the 2'-phosphoryl group, such as U(2'-pp-biotin)pU (4) and U(2'-ps-bimane)pU (5), were rather resistant to hydrolysis. The addition of divalent metal ions (Mg2+, Mn2+, Zn2+, Ca2+, Co2+, and Cd2+) remarkably decreased the rate of 2'-de(thio)phosphorylation of 1 or 2. Among these metal ions, Zn2+ most significantly inhibited the dephosphorylation. On the contrary, trivalent metal ions considerably accelerated the 2'-de(thio)phosphorylation of 1 or 2. The mechanism of 2'-dephosphorylation in the presence and absence of various metal ions is also discussed.
Synthesis and compositions of 2'-terminator nucleotides
申请人:Bodepudi Veeraiah
公开号:US20050037991A1
公开(公告)日:2005-02-17
The invention provides compositions the comprise nucleotides and/or nucleosides having blocking groups at 2′-positions of sugar moieties. Methods of synthesizing these nucleic acids are also provided.
Solid-Phase Synthesis and Hybrization Behavior of Partially 2′/3′-<i>O</i>-Acetylated RNA Oligonucleotides
作者:Jianfeng Xu、Colm D. Duffy、Christopher K. W. Chan、John D. Sutherland
DOI:10.1021/jo5002824
日期:2014.4.18
Synthesis of partially 2'/3'-O-acetylated oligoribonucleotides has been accomplished by using a 2'/3'-O-acetyl orthogonal protecting group strategy in which nonnucleophilic strong-base (DBU) labile nucleobase protecting groups and a LTV-light cleavable linker were used. Strong-base stability of the photolabile linker allowed on-column nucleobase and phosphate deprotection, followed by a mild cleavage of the acetylated oligonucleotides from the solid support with UV light. Two 17nt oligonucleotides, which were synthesized possessing one specific internal 2' or 3'-acetyl group, were used as synthetic standards in a recent report from this laboratory detailing the prebiotically plausible ligation of RNA oligonucleotides. In order to further investigate the effect of 2'/3'-O-acetyl groups on the stability of RNA duplex structure, two complementary bis-acetylated RNA oligonucleotides were also expediently obtained with the newly developed protocols. UV melting curves of 2'-O-acetylated RNA duplexes showed a consistent similar to 3.1 degrees C decrease in T-m per 2'-O-acetyl group.
MILECKI, JAN;DEMBEK, PIOTR;ANTKOWIAK, WIESLAW Z.;GDANIEC, ZOFIA;MIELEWCZY+, NUCLEOSIDES AND NUCLEOTIDES, 8,(1989) N, C. 463-474
Kinetics and Mechanism of Facile and Selective Dephosphorylation of 2‘-Phosphorylated and 2‘-Thiophosphorylated Dinucleotides: Neighboring 3‘−5‘ Phosphodiester Promotes 2‘-Dephosphorylation
2'-phosphorylated and 2'-thiophosphorylated dinucleotides U(2'-p)pU (1) and U(2'-ps)pU (2) were found to undergo facile 2'-specific dephosphorylation at 90 degrees C in neutral aqueous solution to give UpU, and the first-order rate constants of these reactions were determined by HPLC. Particularly, U(2'-ps)pU (2, k = 1.38 +/- 0.4 x 10(-3) s(-1), t(comp) = 1 h) was cleanly dephosphorylated ca. 100 times more rapidly than U(2'-p)pU (1, k = 1.41 +/- 0.05 x 10(-5) s(-1), t(comp) = 72 h). Dephosphorylations of 1 and 2 were faster than those of thymidine 3'-phosphate (8) and thymidine 3'-thiophosphate (9), respectively. The kinetic data observed were independent of the 2'- or 3'-position of the phosphate group and the kind of base moiety. The neighboring 3'-5' phosphodiester function most probably promotes the 2'-dephosphorylation efficiently. A branched trimer, U(2'-pU)pU (3), and related compounds having a substituent on the 2'-phosphoryl group, such as U(2'-pp-biotin)pU (4) and U(2'-ps-bimane)pU (5), were rather resistant to hydrolysis. The addition of divalent metal ions (Mg2+, Mn2+, Zn2+, Ca2+, Co2+, and Cd2+) remarkably decreased the rate of 2'-de(thio)phosphorylation of 1 or 2. Among these metal ions, Zn2+ most significantly inhibited the dephosphorylation. On the contrary, trivalent metal ions considerably accelerated the 2'-de(thio)phosphorylation of 1 or 2. The mechanism of 2'-dephosphorylation in the presence and absence of various metal ions is also discussed.
On Facts and Artefacts: The Difficulty to Evaluate an Artificial Nuclease
作者:Stefan Pitsch、Ute Scheffer、Markus Hey、Andreas Strick、Michael W. Göbel
DOI:10.1002/hlca.200390316
日期:2003.11
general problem of all these studies is to distinguish between real effects and artefacts caused by traces of contaminating natural ribonucleases. We show that methods representing the current state of the art (diethylpyrocarbonate treatment, sterilization, ultrafiltration, etc.) do not sufficiently protect against severe artefacts. However, an incorruptible assay could be found by comparing the cleavage