Heaton P A, Eckstein F
Max-Planck-Institut fur experimentelle Medizin, Göttingen, Germany.
Nucleic Acids Res. 1996 Mar 1;24(5):850-3. doi: 10.1093/nar/24.5.850.
The diastereomers of adenosine and uridine 2',3'-cyclic phosphorothioates were tested as substrates for 2',3'-cyclic nucleotide 3'-phosphodiesterase from bovine brain. The enzyme cleaves the Sp (or exo) diastereomers efficiently, whereas the Rp (or endo) diastereomers are resistant to hydrolysis, even after long incubation. As the enzyme exhibits strong substrate inhibition the precise determination of kinetic parameters posed problems, particularly with phosphorothioates. The stereoselectivity of this enzyme is opposite to that of RNase T1 and RNase A and thus could be a useful complement in determination of the configuration of nucleoside 2',3'-cyclic phosphorothioates resulting from hydrolysis reactions of unknown stereochemical course.
测试了腺苷和尿苷2',3'-环硫代磷酸酯的非对映异构体作为来自牛脑的2',3'-环核苷酸3'-磷酸二酯酶的底物。该酶能有效切割Sp（或外消旋）非对映异构体，而Rp（或内消旋）非对映异构体即使长时间孵育也抗水解。由于该酶表现出强烈的底物抑制作用，动力学参数的精确测定存在问题，尤其是对于硫代磷酸酯。这种酶的立体选择性与核糖核酸酶T1和核糖核酸酶A相反，因此在确定由立体化学过程未知的水解反应产生的核苷2',3'-环硫代磷酸酯的构型时可能是一种有用的补充。
