Which modification should I use for chain termination?
To avoid polymerase extension at the 3' terminus, 2',3'-dideoxynucleoside adn 3'-deoxynucleoside have proved to be effective. 2',3' nucleosides are designed to be used with the 5'- reverse synthesis. However, side reactions during deprotection of the oligonucleotide or enzymatic impurities may free the 3'-hydroxyl group to a small extent. So far, the 3'-propyl phosphate formed using 3'-Spacer C3 CPG has proved to be the simplest and most effective non-nucleosidic blocker of the 3'-terminus.
- 3' Phosphate
- 3' Spacer C3
- 3'-dA, dC, dG, dT
- 2',3'-Dideoxyadenosine (ddA)
- 2,3'-Dideoxycytidine (ddC)
- 2',3'-Dideoxyguanosine (ddG)
- 2',3'-Dideoxythymidine (ddT)
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10/11/2012