Nucleoside alpha-thiotriphosphates, polymerases and the exonuclease III analysis of oligonucleotides containing phosphorothioate linkages.

ABSTRACT: The use of DNA polymerases to incorporate phosphorothioate linkages into DNA, and the use of exonuclease III to determine where those linkages have been incorporated, are re-examined in this work. The results presented here show that exonuclease III degrades single-stranded DNA as a substrate and digests through phosphorothioate linkages having one absolute stereochemistry, assigned (assuming inversion in the polymerase reaction) as S, but not the other absolute stereochemistry. This contrasts with a general view in the literature that exonuclease III favors double-stranded nucleic acid as a substrate and stops completely at phosphorothioate linkages. Furthermore, not all DNA polymerases appear to accept exclusively the (R) stereoisomer of nucleoside alpha-thiotriphosphates [and not the (S

SUBMITTER: Yang Z 

PROVIDER: S-EPMC1888802 | biostudies-literature | 2007

REPOSITORIES: biostudies-literature