Electron microscopic investigations on the structure of lectin I from Viscum album L.

Molecules of mistletoe lectin I (ML I) were investigated electron microscopically by negative staining with uranyl salts. An equilibrium was found between monomers and dimers at the used protein concentration. ML I monomers show a nearly triangular or rounded profile with dimensions of 80 × 90 A. ML I dimers are rod-like particles composed of two triangular parts which are dislocated against each other. In another view the dimers appear thinner without a pronounced substructure. The dimensions of the dimers are 175 × 80 × 60 A.