Functional Domain of Marine Invertebrate Lectin

多乳糖苷的氨基酸序列--结合荧光素从玉米桶中的钙质流体中分离出来， Megabalanus rosa已经决定了。140 K讲座由身份子单位（Mr.22K）组成，其中交叉链接到了连锁干扰债券。该亚单位是在173种氨基酸中含有糖蛋白。64 K讲座由138种氨基酸的四种鉴别子（Mr.16K）组成。子单位是交叉的--被干扰债券链接到C终端段形成dimers。它们有一个域，其中一个域与钙依赖性（C型）动物讲义相同，其中一个是碱性的。通过urea和该课程的其他代理人的退化被高性能尺寸排除色谱和对兔子细胞的攻击活动所跟踪。64 K讲座的亚单元结构在6 M urea和50%的异丙胺中高度稳定，保持了活性，在140 K讲座中容易被去除，一种可光激活的D-半乳糖胺衍生物被准备用光亲和性标签将讲座标记为本地碳酸酯绑定站点。该讲座还被用于对氨基酸酯-结合特性的排序进行各种化学修饰，以使其对氨基酸酯-结合特性负责。对赖氨酸和酪氨酸的修改并不影响他们的活动。However，对色氨酸、arginine和Histidine进行了修改，以完全失去活性物质。用氰化物进行治疗，两个64 K树脂的片段，一个小的一个包含交叉干扰键和一个大的一个对应到碳酸氢盐-识别域，通过凝胶过滤。孤立的域被证明是通过亲和力色谱法在HCI治疗Sepharose 4 B列上保留碳酸氢盐结合活动。上面的结果表明，海洋反转性课程可以用作一个功能域来构建多功能蛋白的各种kinds。

The amino acid sequences of multiple galactose-binding lectins isolated from the coelomic fluid of the acorn barnacle, Megabalanus rosa have been determined. 140K lectin was composed of identical subunits (Mr 22K) which were cross-linked by interchain disulfide bonds. The subunit was a glycoprotein on 173 amino acids. 64K lectin was composed of four identical subunits (Mr 16K) of 138 amino acids. The subunits were crossーlinked by disulfide bonds to form dimers at the C-terminal segments. They had a domain which was homologous with the carbohydrate-recognition domain of the calcium-dependent (C-type) animal lectins. The denaturation by urea and other agents of the lectins was followed by high-performance size exclusion chromatography and agglutinating activity against rabbit erythrocytes. The subunit structure of 64K lectin was highly stable either in 6M urea and 50% isopropanol, sustainig the activity, whereas 140K lectin easily denatured.A photoactivatable D-galactosamine derivative was prepared for the photoaffinity labeling of the lectins to localize carbohydrate binding sites. The lectins were also subjected to various chemical modification in order to ascertain the amino acid residues responsible for its carbohydrate-binding property. Modification of lysine and tyrosine did not affect their activities. However, modification of tryptophan, arginine and histidine led to complete losses of the activities.Upon treatment with cyanogen bromide, 64K lectin yielded two fragments, a small one including interchain disulfide bonds and a large one corresponding to the carbohydrate-recognition domain, by gel filtration. The isolated domain was demonstrated to retain the carbohydrate binding activity by affinity chromatography on a HCI treated Sepharose 4B column.The above results indicate that marine invertebrate lectins can be used as a functional domain to construct various kinds of multifunctional proteins.