Purification and partial characterization of a new melibiose-specific lectin from Bauhinia catingae Harms

Lectins are ubiquitous proteins that selectively bind to carbohydrates, serving as vital models for understanding protein-carbohydrate interactions. While extensively distributed across various life forms, plant lectins, especially from the Leguminosae family, have garnered significant attention. However, limited research exists on lectins from the Caesalpinioideae subfamily, suggesting a source of untapped biotechnological potential. This underscores the imperative for further exploration, particularly in isolating lectins from the Bauhinia genus, which remains relatively understudied, despite harboring lectins with diverse characteristics and promising biotechnological activities. In this study, a novel lectin extracted from Bauhinia catingae Harms seeds (BCL) was isolated in three chromatographic steps. BCL exhibited affinity for galactose and derivatives, akin to other Bauhinia lectins, with SDS-PAGE confirming its molecular weight around 30 kDa. Notably, BCL demonstrated stability across temperature and pH ranges and lacked metalloprotein characteristics. Electrospray ionization mass spectrometry revealed a partial sequence covering 81 % of the total protein sequence with nearly 80 % identity to Bauhinia forficata. Structural analysis suggested a β-sheet-rich secondary structure similar to that of other lectins. Further structural elucidation of BCL is essential to unveil its full potential and applications.