CHIRAL SURFACES IN MICELLES OF ENANTIOMERIC N-PALMITOYL AND N-STEAROYLSERINE

Circular dichroism (CD) spectra were recorded with micellar aggregates of a series of N-palmitoyl and N-stearoyl derivatives of amino acid enantiomers. N-Palmitoyl- and N-stearoYl-L- (or -D-) serine in the micelle form (10(-4) M in aqueous 0.01 M KOH) exhibited a strong CD band centered at 213-215 nm which could be completely abolished by disintegrating the micelles in 50% ethanol. Analogous CD spectra of enantiomeric N-palmitoyl derivatives of tyrosine or proline did not display any exclusive band for the micellar form. The CD spectra of the enantiomeric N-palmitoyl- or N-stearoylserine micelles presumably originated from a repetitive arrangement of the amide planes on the micellar surface. Computer modeling suggested an alternating tilt of the amide planes associated with the formation of parallel spines of -NH...OC- intermolecular hydrogen bonds which cover the micellar surface. Each of such spines has a supramolecular chirality, which is presumably the origin of the observed CD band. The network of such chiral spines forms a unique chiral surface which may bear important implications for surface recognition and catalysis.