Feofanov A V, Sharonov G V, Dubinnyi M A, Astapova M V, Kudelina I A, Dubovskii P V, Rodionov D I, Utkin Yu N, Arseniev A S
Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Mikklukho-Maklaya 16/10, Moscow 117997, Russia.
Biochemistry (Mosc). 2004 Oct;69(10):1148-57. doi: 10.1023/b:biry.0000046890.46901.7e.
Cytotoxins are positively charged polypeptides that constitute about 60% of all proteins in cobra venom; they have a wide spectrum of biological activities. By CD spectroscopy, cytotoxins CT1 and CT2 Naja oxiana, CT3 Naja kaouthia, and CT1 and CT2 Naja haje were shown to have similar secondary structure in an aqueous environment, with dominating beta-sheet structure, and to vary in the twisting angle of the beta-sheet and the conformation of disulfide groups. Using dodecylphosphocholine micelles and liposomes, CT1 and CT2 Naja oxiana were shown to incorporate into lipid structures without changes in the secondary structure of the peptides. The binding of CT1 and CT2 Naja oxiana with liposomes was associated with an increase in the beta-sheet twisting and a sign change of the dihedral angle of one disulfide group. The cytotoxins were considerably different in cytotoxicity and cooperativity of the effect on human promyelocytic leukemia cells HL60, mouse myelomonocytic cells WEHI-3, and human erythroleukemic cells K562. The most toxic CT2 Naja oxiana and CT3 Naja kaouthia possessed low cooperativity of interaction (Hill coefficient h = 0.6-0.8), unlike 10-20-fold less toxic CT1 and CT2 Naja haje (h = 1.2-1.7). CT1 Naja oxiana has an intermediate position on the cytotoxicity scale and is characterized by h = 0.5-0.8. The cytotoxins under study induced necrosis of HL60 cells and failed to activate apoptosis. The differences in cytotoxicity are supposed to be related not with features of the secondary structure of the peptides, but with interactions of side chains of variable amino acid residues with lipids and/or membrane proteins.
细胞毒素是带正电荷的多肽，约占眼镜蛇毒液中所有蛋白质的60%；它们具有广泛的生物活性。通过圆二色光谱法，已证明中亚眼镜蛇的细胞毒素CT1和CT2、泰国眼镜蛇的CT3以及埃及眼镜蛇的CT1和CT2在水性环境中具有相似的二级结构，以β-折叠结构为主，且β-折叠的扭转角度和二硫键的构象有所不同。使用十二烷基磷酸胆碱胶束和脂质体，已证明中亚眼镜蛇的CT1和CT2可掺入脂质结构中，而肽的二级结构无变化。中亚眼镜蛇的CT1和CT2与脂质体的结合与β-折叠扭转增加以及一个二硫键的二面角符号变化有关。这些细胞毒素在对人早幼粒细胞白血病细胞HL60、小鼠骨髓单核细胞WEHI-3和人红白血病细胞K562的细胞毒性和协同作用方面有很大差异。毒性最强的中亚眼镜蛇CT2和泰国眼镜蛇CT3具有低相互作用协同性（希尔系数h = 0.6 - 0.8），这与毒性低10 - 20倍的埃及眼镜蛇CT1和CT2（h = 1.2 - 1.7）不同。中亚眼镜蛇CT1在细胞毒性尺度上处于中间位置，其特征为h = 0.5 - 0.8。所研究的细胞毒素诱导HL60细胞坏死，未能激活细胞凋亡。细胞毒性的差异被认为与肽的二级结构特征无关，而是与可变氨基酸残基的侧链与脂质和/或膜蛋白的相互作用有关。
