43 Journal of Protein Chemistry, Vol. 21, No. 1, January 2002 (© 2002) 0277-8033/02/0100-0043/0 © 2002 Plenum Publishing Corporation Primary Structure Characterization of Bothrops jararacussu Snake Venom Lectin Daniela D. de Carvalho, 1 Sergio Marangoni, 1 and José C. Novello 1,2 Received October 11, 2001 The complete amino acid sequence of the lectin from Bothrops jararacussu snake venom (BJcuL) is reported. The sequence was determined by Edman degradation and amino acid analysis of the S-carboxymethylated BJcuL derivative (RC-BJcuL) and from its peptides originated from enzy- matic digestion. The sequence of amino acid residues showed that this lectin displays the invariant amino acid residues characterized in C-type lectins. Amino acids analysis revealed a high content of acidic amino acids and leucine. These findings suggest that BJcuL, like other snake venom lectins, possesses structural similarities to the carbohydrate recognition domain (CRD) of calcium- dependent animal lectins belonging to the C-type -galactoside binding lectin family. KEY WORDS: Snake venom; Bothrops jararacussu; C-type lectin; amino acid sequence. The sugar-binding activity can be ascribed to a lim- ited portion of most lectin molecules, typically a globular carbohydrate recognition domain of less than 200 amino acids. These molecular regions are designated CRD, and many of them are related in amino acid sequence to each other, having high sequential homology (Weis and Drickamer, 1996). Carbohydrate-binding to CRD is due to a combina- tion of hydrogen bonding to the sugar hydroxyl groups, metal coordination, and van der Waals packing, often in- cluding packing of a hydrophobic sugar face against aro- matic amino acid side chains (Elgavish and Shaanan, 1997). In C-type lectins, galactose specificity is imposed by a glycine-rich loop (Kolatkar and Weis, 1996), and calcium forms direct coordination bonds with the sugar ligand (Weis and Drickamer, 1996). Several lectins have been isolated from snake ven- oms (Hirabayashi et al., 1991; Nikai et al., 1995; Komori et al., 1999; Nikai et al., 2000). They are shown to be composed of two identical subunits with invariant amino acid residues, which are also found in the carbohydrate recognition domain of the C-type lectins (Weis et al., 1. INTRODUCTION Lectins are proteins, or glycoproteins, found in a diverse array of organisms. They consist of a large group of pro- teins with the ability of binding specifically, reversibly, and noncovalently to carbohydrates (Kishore, 1997). Some of these molecules may also contain a second binding site that interacts with a noncarbohydrate ligand. Just as the num- bers of lectins are many, so are the different functions they have (Singh et al., 1999). Although the number of animal lectins continues to increase, it is possible to classify them into five major groups: (1) The C-type or calcium dependent lectins, (2) the galactose-binding galectins, (3) the I-type lectins (including sialoadhesins and other immunoglobulin-like sugar-binding proteins), (4) the lumenal proteins of the ER (endoplasmic reticulum) that interact transiently with gly- coproteins, (5) and the L-type lectins related in sequence to the leguminous plant lectins (Drickamer, 1995). 1 Universidade Estadual de Campinas (UNICAMP), Instituto de Biolo- gia, Departamento de Bioquímica, LAQUIP, Campinas-SP, 13083–970, Brazil. 2 To whom correspondence should be addressed; e-mail: jcn@uni- camp.br 3 Abbreviations: EDTA, ethylenoglycol bis (-aminoethyl ether) N, N´-tetraacetic acid; DTT, dithiothreitol; PTH, phenyl-thio-hidan- toin.