A FLUORESCENCE SPECTROSCOPIC STUDY ON THE BINDING OF MESSENGER-RNA 5'-CAP-ANALOGS TO HUMAN TRANSLATION INITIATION-FACTOR EIF4E - A CRITICAL-EVALUATION OF THE SOURCES OF ERROR

Equilibrium constants for the association of human protein translation initiation factor eIF4E with two mRNA 5'-cap analogs, namely 7-methyl guanosine 5'-triphosphate and P-1-(7-methylguanosine-5') P-3-(guanosin e-5') triphosphate, and with guanosine 5'-monophosphate have been rede termined by the fluorescence quenching method taking the inner filter effect of the cap-analog into account. It has been shown that neglecti ng the latter correction may lead to either underestimation or overest imation of the association constant obtained by applying the Eadie-Hof stee plot: the reasonably firm binding of 7-methylated cap-analogs bec omes underestimated, while the weak binding of nonmethylated nucleotid es becomes overestimated. (C) 1998 Elsevier Science S.A. All rights re served.