Spectroscopy and Recognition Chemistry of Micelles from Monoalkyl Phosphoryl Nucleosides

We describe the properties of aqueous micelles obtained from n-alkyl phosphoryl nucleosides, in particular n-hexadecylphosphoryladenosine (C16-AMP), uridine (C16-UMP), and -cytidine (C16-CMP). These compounds were obtained enzymatically. It is shown that each of these compounds form micelles spontaneously in water with a critical micelle concentration in the range of 20−35 μM and an aggregation number of 69, which indicates that the chemical structure of the bases has no significant influence on the aggregation behavior. UV-absorption and circular dichroic measurements suggest that the nucleoside is in an aqueous environment, as expected from the amphiphilic character of the compounds. UV absorption suggests a moderate self-stacking among the bases for each type of micelle. When we mixed micelles bearing complementary bases with each other (e.g., C16-AMP with C16-CMP), a weak hypochromic effect was observed, which can be taken as an indication of complementary base interaction. However, such electronic perturbation was observed also in noncomplementary bases, e.g., when C16-CMP micelles were mixed with C16-UMP micelles. These micelle data are compared with the corresponding data obtained with liposomes obtained from phosphatidyl nucleosides. All together, these data illustrate a novel type of polymeric nucleoside interaction with which no covalent bonds form among the monomers, and in which the nucleobases are distributed as a supramolecular spherical aggregate.