Screening, structure and usefulness of marine bioactive proteins

1. 从几种海葵的体或噬菌中分离出2种Na^+通道毒素、1种K^+通道毒素、4种新型肽毒素和8种kunitz型蛋白酶抑制剂，并对其进行了完整的测序。在大肠杆菌中成功表达了橡实藤蔓凝集素BRA2和BRA3。重组BRA3的糖结合特异性与天然BRA3相同，而重组BRA2的糖结合特异性与天然BRA2不同，可能是由于缺乏碳水化合物链。从虹鳟卵中分离到两种鼠李鼻结合凝集素（stl）。序列测定显示stl属于一个新的动物凝集素家族。从红藻中分离到一种特异性识别高甘露糖型n -聚糖的有丝分裂凝集素（ESA-2）。它在分子中含有多个重复序列，与某些细菌血凝素具有较高的序列相似性。此外，它还能抑制培养的人肿瘤细胞的生长。采用RT-PCR方法及紫色腺、蛋白腺和中肠的cDNA文库筛选均未获得黑斑海兔紫色液抗菌糖蛋白（applysianin - p） cDNA克隆。这可能表明该基因在被检测的组织中不表达，或者先前确定的该基因的氨基酸序列是不正确的。随着血浆抗体活性的升高，鳗皮黏液的溶血和凝集素活性降低。纯化后的皮肤黏液凝集素对自身嗜中性粒细胞具有拮抗和趋化活性。这些结果意味着表面和内部防御机制的协同作用。凝集素活性低的母亲所生的鲍鱼幼虫对疾病有较高的易感性，说明凝集素活性是鲍鱼抗病的特征之一。

1. Two Na^+ channel toxins, one K^+ channel toxin, four novel peptide toxins and eight Kunitz-type protease inhibitors were isolated from bodies or acrorhagi of several species of sea anemones and completely sequenced.2. Acorn barnacle Megabalanus rosa lectins, BRA2 and BRA3, were successfully expressed in Escherichia coli. The sugara-binding specificity of recombinant BRA3 was the same as that of native BRA3, while recombinant BRA2 showed different sugar-binding specificity from native BRA2 probably due to the absence of carbohydrate chain in the former.3. Two rhamnose-binding lectins (STLs) were isolated from steelhead trout Oncorhynchus mykiss eggs. Sequence determinations revealed that STLs belong to a new family of animal lectins.4. A mitogenic lectin (ESA-2) recognizing specifically high mannnose type N-glycans was isolated from the red alga Euchemuaserra. It contained several repeated sequences in the molecule, showing high sequence similarity with some bacterial hemagglutinins. Furthermore, it inhibited the growth of cultured human tumor cells.5. An aplysianin-P (antibacterial glycoprotein from the purple fluid of sea hare Aplysia kurodai) cDNA clone was not obtained by either RT-PCR method or screening of cDNA libraries from purple gland, albumen gland and midgut. This may suggest that the gene of aplysianin-P is not expressed in the tissues examined or that the previouly determined amino acid sequence of aplysianin-P is incorrect.6. Hemolytic and lectin activities of the eel skin mucus decreased with the rise of antibody activity in the blood plasma. Purified skin mucus lectin was found to have both opsonic and chemotactic activities against own neutrophiles. These results mean the cooperative action of surface and inner defense mechanisms. High disease susceptibility of larvae was seen in abalone born from a mother of low lectin activity, suggesting that the lectin activity is one of the characters of disease resistance in abalone.