Synthetic study of peptide neurotoxins isolated from animals in South East Asia

(1)新型螺壳毒素的合成及二硫配对测定。我们从松果中分离合成了三种新的松果毒素CMrII、CMrIII和CMrV。它们都有三个分子内二硫键。为了确定二硫键对，我们采用选择性两步二硫键形成法合成了CMrII。与天然肽共洗脱表明CMrII具有C1-C4、C2-C5和C3-C6组合。然而，CMrV具有不同的二硫模式。CMrV的复检正在进行中。国外合作者从线虫中分离到了4种新的concontoxin， AmIV、AmVIIA、AmVIIB和AmIX。分别合成了AmIV和AmIX的c端修饰肽和游离肽。HPLC共洗脱表明AmIV和AmIX分别具有游离和修饰的c -末端。合成了AmVIIA和AmVIIB，发现它们具有游离的c -末端。(2) sc…More orpion毒素的二硫化物模式、三维结构与活性的关系。Hefutoxin-1从蝎中分离得到，具有独特的由两个平行螺旋由两个二硫桥连接而成的三维折叠结构，没有任何β片。我们合成了两个在中心环区缺失一个或两个氨基酸残基的hefutoxin-1类似物。酶切缺失类似物表明它们都具有与天然肽相同的二硫对。合成了几种氨基酸取代的类似物进行构效关系研究。从棘蝎毒中分离到5种新的肽毒素HS2388、HS2404、HS2620、HS3019和HS3700。我们将它们全部合成，并确认HS2388和HS2404有修饰的c端，而其他的有游离的c端。CD谱分析和酶切分析表明，HS2388、HS2404、HS2620和HS3019与河富毒素-1具有相同的二硫模式。HS2620的合成类似物表明，第20位的碱基残基干扰了该毒素与K通道的相互作用。少

(1)Synthesis and disulfide pairing determination of novel conotoxins from cone snail.We synthesized three novel conotoxins CMrII, CMrIII, and CMrV isolated from Cones marmoreus. All of them have three intramolecular disulfide bonds. In order to determine the disulfide pairings, we synthesized CMrII by selective two-step disulfide bond formation method. HPLC co-elution with native peptide suggested that CMrII has C1-C4, C2-C5, and C3-C6 combinations. Whereas, it was suggested that CMrV has different disulfide patterns. Re-examination is in progress for CMrV.Four novel conotoxins, AmIV, AmVIIA, AmVIIB, and AmIX were isolated from C. amadis by foreign collaborators. Both C-terminal amidated and free peptides were synthesized for AmIV and AmIX. HPLC co-elution indicated that AmIV and AmIX had free and amidated C-terminals, respectively. AmVIIA and AmVIIB were synthesized and shown to have free C-terminals.(2)Relationships of disulfide pattern, three-dimensional structure and activity of sc … More orpion toxins.Hefutoxin-1 isolated from scorpion Heterometrus fuIvipes adopts a unique three-dimensional fold of two parallel helices linked by two disulfide bridges without any βsheets. We synthesized two analogs of hefutoxin-1 with deletion of one or two amino acid residues at the central loop region. Enzymatic digestion of deletion analogs showed that both of them have the same disulfide pairings as native peptides. Several analogs with amino acid substitution were synthesized for structure-activity relationship study.Five novel peptide toxins HS2388, HS2404, HS2620, HS3019, and HS3700 were isolated from scorpion H, spinifer venom. We synthesized all of them and confirmed that HS2388 and HS2404 have amidated C-terminals, whereas others have free C-terminals. Comparison of CD spectra and enzymatic digestion suggested that HS2388, HS2404, HS2620, and HS3019 have the same disulfide pattern as that of hefutoxin-1. Synthetic analogs of HS2620 suggested that the basic residue at the 20th position interfere the interaction of this toxin to K channels. Less