Characterization of the lectin from the bulbs of Eranthis hyemalis (winter aconite) as an inhibitor of protein synthesis.

The lectin from Eranthis hyemalis has been previously characterized as consisting of two polypeptide chains covalently linked by disulfide bond(s) (Cammue, B. P., Peeters, B., and Peumans, W. J. (1985) Biochem. J. 227, 949-955). We have further characterized the biochemical properties of the lectin and demonstrated that it possesses the property of inhibition of protein synthesis using in vitro eukaryotic translation systems. The protein also possesses antiviral activity against the plant virus, alfalfa mosaic virus, and larvicidal activity against the southern corn rootworm, Diabrotica undecimpunctata howardii, a major insect pest of the maize plant. Both isoelectric focusing on gels and chromatofocusing indicated heterogeneity of the protein, with three species having isoelectric points in the range 4-5. The disulfide bond(s) can be rapidly reduced with beta-mercaptoethanol under native conditions. The reduced alkylated polypeptide chains remain associated under native conditions to form a species, EHL', that elutes at the same position as the native protein and has the same molecular weight by sedimentation equilibrium experiments. However, circular dichroism and fluorescence measurements indicated conformational differences between the species.