The effect of chemical modification on Polygonatum cyrtonema Hua.lectin Ⅱ(PCLⅡ)was investigated in order to elucide the role of tyrosine in the bioactivity of PCL Ⅱ.Modification of tyrosine in PCL Ⅱ with p nitrobenzene sulfonyl fluoride (NBSF) led to a loss of 40% of the mitogenic activity towards T\|cell,but had no effect on hemagglutination.The hemagglutination of PCL Ⅱ also kept no change when modified by 10 mmol/L NAI,while it decreased slightly in 20 mmol/L NAI,which indicated that amino group played marginal role in the binding site,since the thiol group was not essential for the hemagglutination.Modification of PCL Ⅱ with 5 and 10 mmol/L NAI was accompanied by a loss of 30% and 48% of mitogenic activity respectively.When deacetylation by hydroxylamine,PCL Ⅱ almost regained all activity towards T cell,indicating that phenolic hydroxyl group on tyrosine was essential for the mitogenic activity and amino group or thiol group also played marginal role in the course.
