- Hydrolysis of diribonucleoside monophosphate diesters assisted by a manganese(II) complex
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An Mn2+ complex with 2,2′:6′,2″-terpyridine (terpy) was found to promote the hydrolysis of NpN (NpN = diribonucleoside monophosphate diester) efficiently at pH 7.0 and 50 °C under ambient conditions. The structure of the Mn2+ complex involving a phosphodiester molecule, [(terpy)(dpp)MnII(μ-dpp) 2MnII(dpp)(terpy)], dpp = diphenyl phosphate anion, was established by X-ray crystallography, and the coordination mode of Mn 2+ to a phosphodiester molecule was considered.
- Yashiro, Morio,Higuchi, Maiko,Komiyama, Makoto,Ishii, Youichi
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p. 1813 - 1817
(2007/10/03)
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- α-Cyclodextrin-Catalyzed Regioselective P-O(2') Cleavages of 2',3'-Cyclic Monophosphates of Ribonucleosides
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Regioselective P-O(2') cleavages of 2',3'-cyclic monophosphates of cytidine (1a), uridine (1b), adenosine (1c), and guanosine (1d) to the corresponding 3'-monophosphates (IIIa-d) are achieved at pH 11.08, 20 deg C by α-cyclodextrin (α-CyD) as catalyst.The selectivities asymptotically increase with increasing concentration of α-CyD, attaining 98, 94, 76, and 67percent for the cleavages of Ia-d, respectively, at the concentration of 0.05 M α-CyD.In the absence of α-CyD, however, significant concurrent cleavages of the P-O(3') bonds take place and the selectivities for IIIa-d are only 47, 50, 54, and 52percent.The rate of the P-O(2') cleavage of Ia in the α-CyD-Ia complex is 14 times as large as that of free Ia, and the rate of the P-O(3') cleavage in the complex is virtually zero. β- and γ-CyDs show no regioselective catalyses. 1H NMR spectroscopy indicates that the α-CyD-Ia and -Ib complexes are formed by hydrogen bondings and I's are located on the secondary hydroxyl side of the cavity of α-CyD.The selective cleavages of ribonucleotide dimers CpC, CpU, CpA, and CpG to IIIa are also successfully carried out by α-CyD as catalyst.
- Komiyama, Makato
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p. 3046 - 3050
(2007/10/02)
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- REGIOSELECTIVE CLEAVAGE OF DI- AND POLY-RIBONUCLEOTIDES INDUCED BY CYCLODEXTRINS (CYCLOMALTO-OLIGOSACCHARIDES)
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Cyclodextrins (cyclomalto-oligosaccharides, CDs) induce regioselective cleavage of the 3',5'-phosphodiester linkages in di- and poly-ribonucleotides at pH 11.08 and 50 deg C. 0.15M Cyclomaltohexaose (α-CD) mediates the cleavage of CpA, CpC, CpG, and CpU to give 96-97percent of cytidine 3'-phosphate together with adenosine, cytidine, guanosine, and uridine, respectively.In the absence of α-CD, 50-52percent of cytidine 2'-phosphate is formed as by-product. α-CD also promotes the formation of adenosine 3'-phosphate from ApA and ApC, guanosine 3'-phosphate from GpG, and uridine 3'-phosphate from UpU.In contrast, β-CD and γ-CD enhance the formation of the corresponding 2'-phosphates.Regioselective cleavages of poly, poly, poly, and poly are achieved also.
- Komiyama, Makoto
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