Affinity labelling of the tick-borne encephalitis virus RNA replicase proteins by 4-n-exo-base-substituted photoreactive CTP analogs

4-N-exo-base-substituted photoreactive analogs of CTP were designed and synthesized. Two flavivirus proteins NS5 and NS3 are shown to be labelled after RNA synthesis in the presence of the analogs, irradiation by UV-light (313 nm) and subsequent [α-32P]NTP incorporation. 4-N-exo-base-substituted photoreactive analogs of CTP were designed and synthesized. Two flavivirus proteins NS5 and NS3 are shown to be labelled after new affinity labelling procedure: RNA synthesis in the presence of the analogs, irradiation by UV-light (313 nm) and subsequent [α-32P]NTP incorporation.