頁籤選單縮合
題名 | Two Novel α-Neurotoxins Isolated from Taiwan Cobra: Sequence Characterization and Phylogenetic Comparison of Homologous Neurotoxins= |
---|---|
作者 | Hung,Chin-chun; Wu,Shih-hsiung; Chiou,Shyh-horng; |
期刊 | 中央研究院生物化學研究所論文集 |
出版日期 | 19980000 |
卷期 | 24 1998[民87.] |
頁次 | 頁67-74 |
分類號 | 361.19 |
語文 | eng |
關鍵詞 | Snake venom; Postsynaptic neurotoxins; α-cobratoxin; Multiple sequence alignment; Sequence comparison; Phylogenetic tree; |
英文摘要 | Two novel postsynaptic neurotoxins (α-neurotoxins) isolated and purified from the Taiwan cobra venom (Naja naja atra) possess distinct primary sequences and different neurotoxicities as compared with the most abundant and lethal component in the venom, i.e.. cobroloxin characterized before from the same venom. The complete sequences of two neurotoxin analogues were determined by N-terrninal Edman degradation and comparison of amino acid compositions of proteolytic toxin fragments with other homologous toxins of known sequences. The short-chain neurotoxin consists of 61 amino acid residues with eight conserved cysteine residues and is found to show 78% sequence identity with cobroloxin. The other toxin, consisting of 65 residues with ten cysteines, belongs to the family oi long-chain neurotoxins. It is the first long-chain a-neurotoxin reported from the Taiwan cobra. The lethal toxicities of these two novel neurotoxins were much lower than cobrotoxin, albeit with close structural homology among the three toxins in terms of their primary sequences and tertiary structure predicted by homology modeling. Multiple sequence alignment and comparison coupled with construction of a phylogenetic tree for various α-neurotoxins of Naja and closely related genuses have established that all nicotinic α-neurotoxins present in the snake family of Elapidae are closely related to each other, presumably derived from an ancestral polypeptide by gene duplication and subsequent multiple mutational substitutions. |
本系統之摘要資訊系依該期刊論文摘要之資訊為主。