THE CRYSTAL-STRUCTURE OF CANAVALIA-BRASILIENSIS LECTIN SUGGESTS A CORRELATION BETWEEN ITS QUATERNARY CONFORMATION AND ITS DISTINCT BIOLOGICAL PROPERTIES FROM CONCANAVALIN-A

Canavalia brasiliensis lectin was isolated from the seeds of a Brazili an autochthonous Leguminosae plant. Despite extensive amino acid seque nce similarity with Concanavalin A, C. brasiliensis lectin exerts in v itro and in vivo cellular effects that are markedly different from tho se displayed by Concanavalin A. We have solved the crystal structure o f the C. brasiliensis lectin at 3.0 Angstrom resolution. The three-dim ensional structure of the lectin monomer can be superimposed onto that of Concanavalin A with a root-mean-square deviation for all C alpha a toms of 0.65 Angstrom. However, this parameter is 0.84 and 1.62 Angstr om when the C. brasiliensis lectin diner and tetramer, respectively, a re compared with the same structures of Concanavalin A. We suggest tha t these differences in quaternary structure may account for the differ ent biological properties of these two highly related Leguminosae lect ins. (C) 1997 Federation of European Biochemical Societies.