黑色菜豆(Phaseolus sp.)凝集素的纯化和性质

黑色菜豆(phaseolussp.)种子中含有对人A型血专一凝集的凝集素。用猪胃粘蛋白-Sepharose 4B作亲和吸附剂和Sephadex G-200凝胶过滤,可以纯化这种凝集素。纯化的凝集素在pH8.9,Tris-EDTANa_2-borate缓冲液的PAGE中,呈现单一蛋白带;酚-硫酸法测得总糖含量为3.22％。在SDS-PAGE中发现其分子由两种亚基所组成,亚基分子量分别为38,000和35,000。当凝集素浓度分别为0.98μg/ml和1.95μg/ml时能强烈地凝集人A型和AB型血细胞。在凝集素浓度高达500μg/ml时,B型血细胞能发生弱凝集反应,但对O型血和兔红细胞则完全不发生凝集反应。其凝集活性可被GalNAC、L-Fuc、猪甲状腺球蛋白和卵粘蛋白所抑制。该凝集素对人外周血中淋巴细胞的转化率达80％,细胞分裂比率高达37.1％;氨基组成分析表明,凝集素分子中Asp和Glu含量较高,而cys和Met含量很低。

PURIFICATION AND CHARACTERIZATION OF BLACK MEAT-BEAN (PHASEOLUS sp.) LECTIN

An anti-A lectin has been purified from black bean (PAaseolus sp.) by affinity chromatography on hog gastric mucin-Sepharose 4B, followed by gel filtration on Sephadex G-200.The purified lectin gives one band on polyacrylamide gel elec-trophoresis. On SDS-PAGE the purified lectin yields two bands, corresponding to subunits of molecular weight 35,000 and 38,000. The purified lectin contains about 3.22% hexose. This lectin can specifically agglutinate human A and AB erythrocytes at a concentration of 0.98μg/ml and 1.95μg/ml respectively. At 500 μg/ml, it can agglutinate B erythrocytes slightly but can not agglutinate O type and rabbit erythrocytes. The anti-A activity of this lectin can be inhibited by N-Acetyl-galactosamine, L-Fuctose, hog thyroglobulin and ovomucoid. This lectin is a mitogen; it has mitogenic activity on human peripheral blood lymphocytes. Amino acid analyses show the purified lectin molecule has a large content of Aspartic acid and Glutamic acid, and only a small content of Cysteine and Methionine.