Synthesis of 2 '-iodo- and 2 '-bromo-ATP and GTP analogues as potential phasing tools for X-ray crystallography

Ara-adenosine (adenine 9-beta-D-arabinofuranoside) and nm-guanosine (guanin e 9-beta-D-arabinofuranoside) are converted into 2' halogenated ATP and GTP analogues by triflation and subsequent inversion of configuration at C-2'. For the commercially unavailable arn-guanosine a short synthesis starting from guanosine is presented. The nucleotide analogues could serve for the p reparation of heavy atom derivatives of ATP- and GTP-binding proteins usefu l for protein crystal structure determination by MIR/MAD phasing.