Target-directed isolation and identification of a serum lectin from lamprey (Lampetra japonica) by chromatographys and MALDI-TOF/TOF

A 105-kDa polymer lectin was purified from lamprey (Lampetra japonica) serum by chromatography methods including cation ion-exchange chromatography with a SP-Sepharose^TM XL column and size exclusion chromatography with a Superdex 200 column. The target fractions were collected according to the direction of hemagglutinating activity. The results revealed that the active fractions could adsorb on SP-Sepharose column and showed a 280 nm UV absorbance peak corresponding to molecular weights of 105 kDa in the following size exclusion chromatography. The target fractions with hemagglutinating activity were further checked by Native-PAGE and SDS-PAGE. Two single bands at around 105 kDa and 35 kDa were displayed by two electrophoresis methods respectively, indicating that the protein exists as a trimer in solution. After Native-PAGE and SDS-PAGE, two bands were excised from the gels respectively and further identified by MALDI-TOF/TOF as serum lectin (gi:13094239). The lectin was able to agglutinate rabbit red blood cells (RRBCs) and sheep red blood cells (SRBCs) in vitro. The lectin isolated from lamprey serum in the current study might be helpful for deeply understanding the innate immune molecules dependent immune defence in jawless vertebrates which have been proved recently that they possess a lymphocyte-based system of anticipatory immunity with variable lymphocyte receptors as mediators.