A　novel　lectin,　CLSL,　was　purified　from　Chinese　leek　seeds　by　ion　exchange　chromatography　on　SP　Sephadex　C-25　and　gel　filtration　chromatography　on　Sephadex　G50.　The　lectin　had　a　molecular　weight　of　23.6　kDa　and　was　composed　of　two　identical　subunits　linked　by　disulfide　bonds,　a　conclusion　based　on　SDS-PAGE　under　reducing　and　nonreducing　conditions.　CLSL　was　a　glycoprotein　with　a　carbohydrate　content　of　3.6%.　It　exerted　potent　agglutinating　activity　against　rat　red　blood　cells　at　a　concentration　of　8.9　mu　g/mL.　Hemagglutination　of　rat　erythrocytes　was　inhibited　by　d-fructose,　mannitol,　and　sorbose　at　the　concentration　of　20　mM.　The　hemagglutinating　activity　of　CLSL　was　maintained　at　100　degrees　C　for　60　min　and　under　acidic　pH　conditions　but　was　lost　at　neutral　and　alkaline　pH　conditions.　The　hemagglutinating　activity　was　stimulated　by　Ca2+,　Fe2+,　and　Cu2+　but　inactivated　by　Ba2+　at　a　concentration　of　10　mM.　Ba2+-mediated　inactivation　of　CLSL　was　caused　by　CLSL　conformational　change　induced　by　barium　ions,　according　to　the　results　of　circular　dichroism　and　fluorescence　spectroscopy.　Deconvolution　of　the　CLSL　circular　dichroism　indicated　that　it　was　an　a-helical　lectin　with　alpha-helix　and　beta-fold　contents　of　35.8%　and　8.6%,　respectively.　CLSL　could　also　selectively　inhibit　cell　proliferation.