Screening, structure and usefulness of marine bioactive proteins

1.从几种海葵体内分离得到2种Na~+通道毒素、1种K~(2+)通道毒素、4种新的多肽毒素和8种库尼茨型蛋白水解酶抑制物，并进行了全序列测定。成功地在大肠杆菌中表达了橡子藤壶Megabalanus Rosa凝集素BRA2和BRA3。重组BRA3的糖结合专一性与天然BRA3相同，而重组BRA2与天然BRA2的糖结合专一性不同，可能是由于重组BRA2中没有糖链所致。从银鱼卵中分离到两种鼠李糖结合凝集素(STL)。序列测定表明，STL属于一个新的动物凝集素家族。从红藻Euchemuasera中分离到一种能识别高甘露糖型N-糖链的有丝分裂凝集素(ESA-2)。它在分子中含有多个重复序列，与一些细菌血凝素具有很高的序列相似性。此外，它还能抑制培养的人肿瘤细胞的生长。无论是通过RT-PCR方法还是从紫腺、蛋白腺和中肠中筛选出抗菌糖蛋白P(Aplysianin-P)的cDNA克隆，均未获得。这可能表明在所检测的组织中不表达Aplysianin-P基因，或者先前确定的Aplysianin-P的氨基酸序列是错误的。鳗鱼皮肤粘液的溶血活性和凝集素活性随血浆中抗体活性的升高而降低。纯化的皮肤粘液凝集素对自身中性粒细胞具有调理和趋化活性。这些结果意味着表面防御机制和内部防御机制的协同作用。在凝集素活性较低的母体中，幼鲍对疾病的敏感性较高，提示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.