The novel fluorescent CDP-analogue (P-beta)MABA-CDP is a specific probe for the NMP binding site of UMP/CMP kinase

Direct thermodynamic and kinetic investigations of the binding of nucleotid es to the nucleoside monophosphate (NMP) site of NMP kinases have not been possible so far because a spectroscopic probe was not available. By couplin g a fluorescent N-methylanthraniloyl-(mant) group to the beta-phosphate of CDP via a butyl linker, a CDP analogue [(P-beta)MABACDP] was obtained that still binds specifically to the NMP site of UmpK(dicty), because the base a nd the ribose moieties, which are involved in specific interactions, are no t modified. This allows the direct determination of binding constants for i ts substrates in competition experiments.