铜绿微囊藻毒株M.8641的毒素

M.8641是从武汉东湖分离培养的一株有毒的铜绿微囊藻(Microcystis aeruginosa),它产生两种环状短肽肝毒素。经凝胶过滤及HPLC等过程纯化,Waters Pico Tag系统测定,其主毒素(毒素Ⅰ)的氨基酸组成为:Glu(1),β-Masp(1),Ala(Ⅰ),Arg(2),Mdha(1),FAB-MS和MS/MS测定分子量为m/z1038,元素组成为C_(49)H_(76)O_(12)N_(13)。毒素Ⅱ的氨基酸组成,除一分子Arg为Leu取代外,其余与毒素Ⅰ相同,分子量m/z 994,分子式C_(49)HT_(75)O_(12)N_(10)。毒素Ⅰ和Ⅱ的毒性分别为129和42μg/kg(i.p.),二者在细胞中的含量各为0.12及0.01mg/kg。FLC测定表明M.8641的两种毒素与MCYST-RR和-LR有相同的Rf值。从氨基酸组成、分子量、分子式及毒性等资料分析,亦证明毒素工相当于MCYST-RR,毒素Ⅱ相当于MCYST-LR。

Toxins from Microcystis Aeruginosa Strain M.8641

The toxic Microcystis aeruginosa strain M. 8641 which was isolated from the lakc Dunghu, Wuhan, produced two kinds of cyclic heptapeptide hepatotoxins. The toxins were isolated and purified through gel filtration and high performance liquid chromatography (HPLC) and determined the structure with Waters Pico Tag system and MS. Its main toxin (Toxin Ⅰ ) contained six amino acids: Glu(1), β-methyl-Asp(1), Ala(1), Arg(2), Methyl-dehydro-Ala(1). FAB-MS and MS/MS analysis showed that the molecular weight was 1038,with the formula of C_(49)H_(76)O_(12)N_(13)· Minor toxin (Toxin Ⅱ) had the same amino acids composition as Toxin Ⅰ, except one of Arg was substitued with Leu. Molecular weight was 994, with formula ofC_(49)H_(75)O_(12)N_(10). The toxicity (LD_(50)) of Toxin Ⅰ and Toxin Ⅱ were 129 and 42μg/kg(i. p.), and the toxin contents in algal cells were 0.12 and 0.01 mg/g(dry wt.)respectively. Thin-layer chromatography also indicated that the R_f value of Toxin Ⅰ (Ⅱ) was the same as MCYST-RR(-LR). It was concluded that Toxin Ⅰ of M.8641 was similar to the MCYST-RR, and Toxin Ⅱ similar to the MCYST-LR.