| A lectin,named IOL,was isolated and purified from a brown marine alga Ishige okamurae by extraction with PBS,followed by ammonium sulfate precipitation and a combination of ion-exchange chromatography on DEAE-Sepharose fast flow and gel filtration on Sephadex G-100,and the lowest agglutinating concentration of IOL tested with erythrocytes of rabbit was about 156.25μg/mL.It was proved to be homogeneous by SDS-PAGE,authour measured subunit raletive molecular mass to be about 45 KDa.The biochemical characteristics of IOL were studied.IOL contained 17.877% neutral saccharide.Its absorption peak of UV was at 269.3nm.In its amino acid composition,it had the highest content of Glu,followed by Asp,the lowest content was Met,but there was lack of Try.Agglutinating activities of IOL was only inhibited by barley-sugar.It was stable with activity at pH 4.0～9.0.It had high heat tolerance,and its peak temperature was 80℃.The addition of divalent metals(Zn2+,Mg2+)influence the activity of the lectin.The study on biologocal activity of IOL showed that it had different effects on 7 species of tested fungi(the growth of hyphal and spore germination)and 11 species of bacteria.IOL can agglutinate Scenedesmus obliquus,Dicrateria zhanjiangensis and Pavlova viridis and had effect on growth and content of chlorophyll-a of algae tested,it inhibited growth of Goniaulax polyramna and Phaeocystis globosa and reduced their content of chlorophyll-a,but promoted growth of Platymonas subcordiformis, Scenedesmus obliquus and Rhodella reticulata and increased content of chlorophyll-a.
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