Purification and characterization of a carbohydrate-binding peptide from Bauhinia purpurea lectin.

In order to examine the correlation between the amino acid sequence and sugar binding specificity of Bauhinia purpurea lectin (BPA), a galactose and lactose binding lectin, a peptide which interacts with lactose was purified from an Asp-N endoproteinase digest of BPA by means of affinity chromatography on a column of lactose-Sepharose. The amino acid sequence of this peptide is Asp-Thr-Trp-Pro-Asn-Thr-Glu-Trp-Ser. A tryptic fragment having the ability to interact with lactose was also purified and found to contain the above sequence, consisting of 9 amino acids. The chemical synthesis of this peptide was carried out by the solid-phase method and the synthetic peptide was found to exhibit lactose binding activity in the presence of calcium.