[Water-soluble derivatives of factor IA of pristinamycins. Interaction with the bacterial ribosome].

The IA component of pristinamycins is a depsipeptide with a bacteriostatic effect on Gram positive bacteria. IA is made bactericidal by association with the IIA component of pristinamycins. Use of IA is limited because of its poor solubility in water. For this reason several water soluble IA derivatives have been synthesized. As for IA, these derivatives are fluorescent, a property used to study the binding of each compound to bacterial ribosomes of Escherichia coli (G-) and Staphylococcus aureus (G+). Two different techniques were used: direct study of fluorescence of the ribosome-antibiotic complex, and study of polarization of the fluorescence of the antibiotic bound to its receptor site. In addition to determination of binding parameters, these techniques can evaluate molecular synergy between pristinamycin IA (PIA) derivatives and pristinamycin IIA (PIIA) derivatives. MICs for the tested molecules correlate strongly with their binding parameters.