Preparation and purification of 5'-amino-5'-deoxyguanosine-5'-N-phosphoramidate and its initiation properties with T7 RNA polymerase.

5'-Amino-5'-deoxyguanosine-5'-N-phosphoramidate (GNHP) was synthesised in four steps from guanosine. Its identity was confirmed using spectroscopic and kinetic studies. A chromatographic method for the purification of this unstable compound was developed. GNHP was found to initiate T7 RNAP promoted transcriptions to afford 5'-O3P-NH-RNA, which hydrolyses readily to yield 5'-H2N-RNA that can be conjugated to activated esters.