Bjergårde K, Dahl O
Department of Chemistry, HC Orsted Institute, University of Copenhagen, Denmark.
Nucleic Acids Res. 1991 Nov 11;19(21):5843-50. doi: 10.1093/nar/19.21.5843.
Oligonucleoside phosphorodithioates 1 are modified DNA sequences with potential use as antisense oligonucleotides. The preparation of up to 20-mers containing all four bases by solid phase synthesis is described, with details on the preparation of the four monomer units (protected nucleoside thiophosphoramidites 2), the conditions used for the assembly of the strands with up to 19 phosphorodithioate linkages, and the purification and characterisation of the products. Full-length homogeneity of HPLC-purified all-phosphorodithioate products is demonstrated by PAGE, but 31P NMR discloses the presence of phosphorothioate impurities (typically 8-9%), the origin of which is discussed. Oligonucleoside phosphorodithioates are freely soluble in water at neutral or basic pH, and are very stable towards oxidation, hydrolysis, and nuclease cleavage. Their ability to hybridize to complementary DNA has been studied by UV melting point (Tm) measurements. The observed depression of Tm, 0.5-2 degrees C per phosphorodithioate linkage, is higher that the 0.4-0.6 degrees C found for phosphorothioates.
寡核苷酸二硫代磷酸酯1是经过修饰的DNA序列，具有用作反义寡核苷酸的潜在用途。本文描述了通过固相合成制备包含所有四种碱基的长达20聚体的方法，详细介绍了四种单体单元（受保护的核苷硫代磷酰胺2）的制备、用于组装具有多达19个二硫代磷酸酯键的链的条件以及产物的纯化和表征。通过PAGE证明了HPLC纯化的全二硫代磷酸酯产物的全长均一性，但31P NMR揭示了硫代磷酸酯杂质的存在（通常为8-9%），并讨论了其来源。寡核苷酸二硫代磷酸酯在中性或碱性pH下可自由溶于水，并且对氧化、水解和核酸酶切割非常稳定。通过紫外熔点（Tm）测量研究了它们与互补DNA杂交的能力。观察到的Tm降低，每个二硫代磷酸酯键为0.5-2℃，高于硫代磷酸酯的0.4-0.6℃。
