title: Absolute configuration of the diastereomers of adenosine 5'-O-(1-thiotriphosphate): consequences for the stereochemistry of polymerization by DNA-dependent RNA polymerase from Escherichia coli.
abstract: The diastereomers of uridyl-(3'-5')adenyl-O,O-phosphorothioate [Up(S)A] have been separated by high-performance liquid chromatography. Their identification as RP and SP follows from the RNase A digestion of these products. It was then shown, by the same method, that the R isomer is hydrolyzed by snake venom phosphodiesterase (PDEase) approximately 500 times faster than the S isomer. Similarly, the stereoisomer of adenosine 5'-O-(1-thiotriphosphate) (ATPalphaS), until now arbitrarily designated as isomer B, is hydrolyzed ca 400 times faster by PDEase than is isomer A. From these results it is concluded that the R isomers of Up(S)A and ATPalphaS, isomers B, have the same absolute configuration. It then follows that isomer A of ATPalphaS, the preferred of the two isomers as substrate for DNA-dependent RNA polymerase, has the S configuration. The implications for the stereochemistry of action of the latter enzyme are discussed.
mesh_terms: D000255:Adenosine Triphosphate / Q000031:analogs & derivatives*; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology*; D009690:Nucleic Acid Conformation; D013237:Stereoisomerism; D013873:Thionucleotides
chemical_list: D013873:Thionucleotides; D000255:Adenosine Triphosphate; D012321:DNA-Directed RNA Polymerases