Department of Chemistry and Biochemistry, Florida Atlantic University, Boca Raton, FL 33431, USA.
Biopolymers. 2011;96(2):158-65. doi: 10.1002/bip.21406.
The 83-residue conopeptide (p21a) and its corresponding nonhydroxylated analog were isolated from the injected venom of Conus purpurascens. The complete conopeptide sequences were derived from Edman degradation sequencing of fragments from tryptic, chymotryptic and cyanogen bromide digestions, p21a has a unique, 10-cystine/5-disulfide 7-loop framework with extended 10-residue N-terminus and a 5-residue C-terminus tails, respectively. p21a has a 48% sequence homology with a recently described 13-cystine conopeptide, con-ikot-ikot, isolated from the dissected venom of the fish-hunting snail Conus striatus. However, unlike con-ikot-ikot, p21a does not form a dimer of dimers. MALDI-TOF mass spectrometry suggests that p21a may form a noncovalent dimer. p21a is an unusually large conotoxin and in so far is the largest isolated from injected venom. p21a provides evidence that the Conus venom arsenal includes larger molecules that are directly injected into the prey. Therefore, cone snails can utilize toxins that are comparable in size to the ones commonly found in other venomous animals.
从 Conus purpurascens 的注射毒液中分离出 83 个残基的 conopeptide（p21a）及其相应的非羟化类似物。完整的 conopeptide 序列是通过胰蛋白酶、糜蛋白酶和溴化氰消化片段的 Edman 降解测序得出的，p21a 具有独特的 10 个半胱氨酸/5 个二硫键 7 环框架，分别带有扩展的 10 个残基 N 端和 5 个残基 C 端尾巴。p21a 与最近从鱼猎蜗牛 Conus striatus 解剖毒液中分离出的 13 个半胱氨酸 conopeptide con-ikot-ikot 具有 48%的序列同源性。然而，与 con-ikot-ikot 不同，p21a 不会形成二聚体的二聚体。MALDI-TOF 质谱表明，p21a 可能形成非共价二聚体。p21a 是一种异常大的 conotoxin，到目前为止是从注射毒液中分离出的最大的 conotoxin。p21a 提供了证据表明 Conus 毒液库包括直接注入猎物的更大分子。因此，圆锥蜗牛可以利用与其他有毒动物中常见的大小相当的毒素。
