Assignment of lectins specific for D-galactose or N-acetyl-D-galactosamine to two groups, based on their circular dichroism.

The circular dichroism (CD) spectra of thirteen lectins, most being specific for D-galactose or N-acetyl-D-galactosamine, were compared. Two groupings are proposed on the basis of the CD in the near-ultraviolet region. Group one comprises the lectins from Arachis hypogaea, Glycine max, Phaseolus coccineus, P. lunatus, P. vulgaris, and Vicia villosa, and group two comprises lectins from Caragana arborescens, Cytisus sessilifolius, Dolichos biflorus, Griffonia simplicifolia, and Wisteria floribunda. The CD spectra of lectins from Bauhinia purpurea and Sophora japonica were different from any of the other lectins. CD difference spectra produced by the two sugars were distinctive for each protein, suggesting that the combining sites of these lectins are not homologous despite similarities in specificity and that the CD spectral similarities arise from residues in other, more homologous regions of the proteins.