3'-AMINO-MODIFIED NUCLEOTIDES USEFUL AS POTENT CHAIN TERMINATORS FOR CURRENT DNA-SEQUENCING METHODS

We describe the synthesis of modified nucleoside triphosphates of the four DNA bases containing a 3'-amino group which were prepared from the corresponding 3'-azido derivatives. Introduction of the triphosphate and subsequent reduction of the N3 to the NH2 group led directly to the target molecules 6a-d. Furthermore, 3'-amino-2',3'-dideoxynucleoside 5'-triphosphates proved to be potent inhibitors of the enzymatic synthesis of DNA catalyzed by the standard sequencing enzymes T7 DNA polymerase, sequenase version 2.0, Thermus aquaticus DNA polymerase, and Thermus thermophilus DNA polymerase. Both radioactive and fluorescent sequencing methods were applied successfully to the 3'-amino-modified terminators. Investigations in view of using these chain terminators according to Sanger's sequencing method for fluorescence labeling were done.