Abstract:

Purpose: To purify lectin from tartary buckwheat (TBL) and identify its hemagglutination and enzymatic activity.
Methods: TBL was extracted and purified by ammonium sulfate precipitation, dialysis, and anion exchange chromatography.
Periodic acid-Schiff (PAS) staining was used to identify its glycoprotein nature and sulfuric acid-phenol method was used
to measure the sugar contents. The hemagglutination activity and sugar binding specificity of the purified TBL were tested
by hemagglutination reaction and hemagglutination inhibition assays, and the phosphatase activity was measured by using
4-nitrophenyl phosphate disodium salt hexahydrate (pNpp) as the substrate. Results: The purified TBL displayed a single
band and a molecular weight of 62 kD, as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDSPAGE).
PAS staining indicated that TBL was a glycoprotein with a sugar content of 5.8%. Hemagglutination reaction
demonstrated that TBL could agglutinate the O type of human blood with titer of 15 μg/mL. The hemagglutination activity
was inhibited by D-glucose and D-mannose, from which, TBL can be deduced as a mannose-binding lectin. Further
experiments demonstrated that TBL had phosphatase activity with a Michaelis constant Km of 9.86×10－3 mol/L. Conclusions:
The TBL obtained in this study was a mannose-binding lectin (MBL) with enzymatic functions.

Key words: tartary buckwheat, lectin, glycoprotein, phosphatase