Esa Mäki

Towards Nucleotide Prodrugs Derived from 2,2-Bis(hydroxymethyl)malonate and Its Congeners: Hydrolytic Cleavage of 2-Cyano-2-(hydroxymethyl)-3-methoxy-3-oxopropyl and 3-(Alkylamino)-2-cyano-2-(hydroxymethyl)-3-oxopropyl Protections from the Internucleosidic Phosphodiester and Phosphorothioate Linkages

Thymidylyl-(3′5′)-thymidine (TpT) and its stereoisomeric phosphoromonothioate analogs [P(R)]- and [P(S)]-Tp(s)T having the phosphate or thiophosphate linkage protected with a 2-cyano-2-{[(4,4′-dimethoxytrityl)oxy]methyl}-3-methoxy-3-oxopropyl group (see 5a,b), as well as [P(R)]-Tp(s)T bearing a S-(2-cyano-2-{[(4,4′-dimethoxytrityl)oxy]methyl}-3-oxo-3-[(2-phenylethyl)amino]propyl) protection (see 5c), were prepared. The kinetics of the cleavage of the protecting group from the corresponding detritylated compounds 6a–c was studied over a pH range from 2 to 7. All compounds undergo a hydroxide-ion-catalyzed reaction that releases the unprotected TpT (7a) or Tp(s)T (7b), in all likelihood by departure of the hydroxymethyl group as formaldehyde and concomitant elimination of the phosphodiester or phosphorothioate from the resulting carbanion. The half-life for the deprotection of 6a and 6b is ca. 6 s at pH 7 and 25°, and that of 6cca. 600 s. The reasonably fast release of Tp(s)T from 6c offers a novel method for temporary intrachain attachment of peptides to oligonucleotides to enhance the cellular uptake.

Cu2+TerPy complexes as catalysts of the cleavage of the 5'-cap structure of mRNA.

Cu 2+TerPy is a fairly good catalyst of the cleavage of dinucleoside triphosphates, but its efficiency is not suffiecient for the use in artificial RNA cleaving enzymes. The present work is aimed at improving the catalysis by Cu 2+TerPy with additional catalysts. Electrophilic and general acid catalysis have been studied and bifunctional catalysts have been synthesized. The most efficient catalysis was achieved with a Cu 2+TerPy-dimer.

Bimetallic Cu2+ complexes of bis-terpyridine ligands as catalysts of the cleavage of mRNA 5′-cap models. The effect of linker length and base moiety

Ligands, where two terpyridine units are linked via an alkyl chain of three to five methylene units, have been synthesized. Their Cu2+ complexes have been studied as catalysts for the hydrolysis of the triphosphate bridge of three different dinucleoside triphosphates. The results show that the bimetallic complexes are up to 600 times more efficient catalysts than monomeric Cu2+-TerPy, and up to 5 × 105-fold rate enhancement in comparison to the uncatalysed reaction, is achieved. However, the catalytic activity strongly depends on the length of the linker and the base composition of the substrate. The differences can be attributed to interactions between the Cu2+-TerPy and nucleic acid base moieties as well as steric factors that may hinder the productive interaction between the substrate and the catalyst.

Preparation, hydrolysis and intramolecular transesterification of 3'-deoxy-3'-thioinosine 3'-S-dimethylphosphorothiolate.

Abstract The hydrolytic reactions of the dimethyl ester of 3′-deoxy-3′-thioinosine 3′-S-phosphorothiolate have been followed over a wide aciditty range by HPLC. At pH > 3, only hydroxide ion catalyzed isomerization to the 2′-dimethylphosphate takes place, whereas under more acidic conditions hydrolysis to the 2′-monomethylphosphate and 3′-S-monomethylphosphorothiolate competes. The latter is the only product accumulating in very acidic solutions (1 M hydrochloric acid). Mechanisms of the reactions are discussed.