Novel isosteric, isopolar phosphonate analogs of oligonucleotides: Preparation and properties.
Tocik, Z.; Barvik Jr., I.; Budesinsky, M. etc.,
Biopolymers, 83 400 - 413 (2006)
A synthetic approach leading to novel-type modified oligothymidylates containing an isosteric, isopolar, enzyme-stable C3'-O-P-CH2-O-C4" phosphonate alternative to phosphodiester internucleotide bond was elaborated. The suitable monomers were prepared from 4'-phosphonomethoxy derivatives of alpha-L-threo and beta-D-erythro-2',5'-dideoxythymidine, which were considered interesting as structurally related to nucleoside 5'-monophosphates. The phosphotriester method was applied to the automated synthesis of both homooligomeric phosphonate 15-mer chains and alternating phosphonate-phosphate constructs. The fully modified homooligomers did not hybridize while homooligomers with alternating sequences containing alpha-L-threo-configured units (but not beta-D-erythro-) showed a significant decrease in T-m values in comparison with natural dT(15). For a comparative study, phosphodiester 4'-CH3-substituted oligothymidylate was synthesized and physical studies (NMR, CD, MDS modeling) were undertaken to shed more light on the changes in conformational behavior arising from the chosen structural alterations.