Bauhinia purpurea agglutinin or lectin (BPA/BPL) was isolated from camel’s foot tree. BPA is a tetrameric lectin with a molecular weight of 195,000 and an isoelectric point between pH 4.6 and pH 6.0. Binding appears to be highest for glycoconjugates containing galactosyl (beta-1,3)N-acetylgalactosamine structures but oligosaccharides with a terminal beta-linked N-acetylgalactosamine can also bind. BPA is lactose-specific and elutes with the sugar lactose. It has specificity for blood groups A, B, O (-SA). Treatment of erythrocytes with neuraminidase or trypsin will increase the agglutination reaction, indicating that the receptor is masked by terminal carbohydrates. Although binding specificity is similar to that of peanut agglutinin, tissue staining patterns of these two lectins are distinct.