Optical rotatory dispersion and circular dichroism spectra of several mono- and oligosaccharides are presented, as well as spectra of samples of teichoic acid, W-acetylneuraminic acid, W-acetylneuraminyllactose, and colominic acid, a polymer comprising repeating units of W-acetylneuraminic acid. Attention is focused on the optical activity generated by the 2-acetamido chromophore, common to all compounds examined. The circular dichroism spectra confirm the reality and spectral location of the Cotton effects in those optical rotatory dispersion spectra which have been previously reported. On the basis of the size of the Cotton effect troughs of these compounds and of other oligosaccharides whose rotations are given in previously published reports, it is possible to arrange the oligosaccharides containing W-acetyl-Dglucosamine residues into three groups: (a) oligosaccharides in which the W-acetyl-D-glucosamine residue is s linked but unsubstituted; these compounds show the smallest Cotton effect troughs near 220 mμ (smaller than -2500 (deg cm2)/dmole); (b) oligosaccharides which have their W-acetyl-D-glucosamine residues substituted either on C-3or C-4 by β-D-Gal or α-L-Fuc-( 1 → 2)-β-D-Gal; these compounds have intermediate values for [w]trough-[m]300mμ. (between. 3000 and.9000 (deg cm2)/dmole); (c) oligosaccharides in which the W-acetyl-D-glucosamine residue is disubstituted; these compounds have the largest corrected trough rotations (greater than -9000 (deg cm2)/dmole). The circular dichroism spectra agree with the optical rotatory dispersion data ordering except in one instance: lacto-W-fucopentaose I exhibits a much more intense band near 210 mμ than does lacto-W-fucopentaose II, whereas the reverse is true in the optical rotatory dispersion spectra. The discrepancy is resolved by casting the data in such a way as to take into account the strong influence of monofucosyl substitution on the W-acetyl-D-glucosamine Cotton effects and ellipticity bands. Tentative rules are proposed which may allow decisions to be made as to the nature and position of substituents on Wacetyl- D-glucosamine residues in oligo- and polysaccharides. It is shown that the W-acetyl-D-glucosamine residues in teichoic acids dominate the shape and largely determine the intensity of optical rotatory dispersion spectra of these polymers. While the optical rotatory dispersion and circular dichroism studies cannot distinguish mixtures of α-and β-teichoic acids from both linkages on a single polyribitol phosphate backbone, which is readily demonstrated immunochemically, they do provide a rapid estimate of the proportion of a to s in each case. The great differences in spectra of colominic acid and of its constituent Wacetylneuraminic acid suggest a conformational dependence of the optically active absorption bands in the polymer. This finding and the possible applicability of the work reported here to diverse immunochemical studies are discussed. © 1969, American Chemical Society. All rights reserved.
