Barbondes S H, Haywood P L
Biochim Biophys Acta. 1979 Jan 19;550(2):297-308. doi: 10.1016/0005-2736(79)90216-5.
Extracts of the cohesive forms of the cellular slime molds Dictyosteliym discoideum, Dictyostelium mucoroides and Dictyostelium purpureum contain lectin activity, assayed as hemagglutination activity. The lectin activity from each species binds quantitatively to Sepharose 4B and can be eluted with D-galactose. The resultant purified lectins are abundant proteins representing, in the case of D. purpureum, up to 5% of the total soluble protein of cohesive cells. The preparations from each species are similar but distinct in amino acid composition and other properties. Each purified preparation gives rise to two protein bands on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with the major band representing as little at 77% (D. purpureum) and as much as 96% (D. mucoroides) of the total protein in the two bands. The molecular weights of the pair of bands were different for each species, ranging between about 23 000 and 26 000. The two bands are believed to represent subunits of lectins made up of either one or a combination of these two proteins. The apparent molecular weights of the purified lectin activities determined by sucrose density gradient centrifugation were all in the range of 100 000. N-Acetyl-D-galactosamine was a potent inhibitor of the hemagglutination activity of each perparation; but there were some differences in the relative inhibitory potency of a number of other saccharides. Antiserum raised against each preparation, as well as univalent antibody fragments derived from these antisera, reacted best with the antigens to which they were raised; but showed some cross reaction measured both by precipitin reactions and by inhibition of hemagglutination activity of the purified lectins. The differences between the lectins from the different species could be trivial; but they also could be important for defining specific properties of these three species which reliably segregate into colonies of a single species when grown in mixed culture.
细胞黏菌盘基网柄菌、毛霉状盘基网柄菌和紫色盘基网柄菌的黏聚形式提取物含有凝集素活性，通过血细胞凝集活性进行测定。每个物种的凝集素活性都能与琼脂糖4B定量结合，并且能用D-半乳糖洗脱。得到的纯化凝集素是丰富的蛋白质，就紫色盘基网柄菌而言，占黏聚细胞总可溶性蛋白质的5%。每个物种的制剂在氨基酸组成和其他特性上相似但又有区别。每种纯化制剂在十二烷基硫酸钠-聚丙烯酰胺凝胶电泳上产生两条蛋白带，主要条带在两条带中的总蛋白中所占比例低至77%（紫色盘基网柄菌），高至96%（毛霉状盘基网柄菌）。每个物种的这一对条带的分子量不同，范围在约23000至26000之间。这两条带被认为代表由这两种蛋白质中的一种或组合构成的凝集素亚基。通过蔗糖密度梯度离心法测定的纯化凝集素活性的表观分子量都在100000范围内。N-乙酰-D-半乳糖胺是每种制剂血细胞凝集活性的有效抑制剂；但许多其他糖类的相对抑制效力存在一些差异。针对每种制剂产生的抗血清以及从这些抗血清衍生的单价抗体片段，与产生它们的抗原反应最佳；但通过沉淀反应和纯化凝集素血细胞凝集活性抑制测定都显示出一些交叉反应。不同物种凝集素之间的差异可能微不足道；但对于定义这三个物种的特定特性可能也很重要，当它们在混合培养中生长时能可靠地分离成单一物种的菌落。
