Morris P W, McSwine R
Int J Pept Protein Res. 1983 Nov;22(5):597-602. doi: 10.1111/j.1399-3011.1983.tb02134.x.
10(-4) cleavage of alpha-amanitin after the procedure of Wieland & Fahrmeir (1) but without prior protective methylation of the 6'-hydroxyl of the tryptophan residue affords the alpha-amanitin aldehyde in 45% yield. The aldehyde was found to exhibit Ki = 3.0 and 12 microM for Drosophila melanogaster and wheat germ RNA polymerase II, respectively. This value is approximately 100-fold greater than for the parent alpha-amanitin. Treatment of the alpha-amanitin aldehyde with 2,4-dinitrophenylhydrazine in CH3OH, CH3CN, or dimethylsulfoxide yielded three products. Two of these did not contain the 2,4-dinitrophenyl moiety, showed Ki = 3.3 and 0.26 microM for wheat germ RNA polymerase II (alpha-amanitin, Ki = 0.09 microM), and accounted for 30-60% and 3% of the input alpha-amanitin aldehyde, respectively. The alpha-amanitin-2,4 dinitrophenylhydrazone was recovered in less than 10% yield regardless of reaction condition and showed a Ki = 0.26 microM on wheat germ RNA polymerase II. This hydrazone establishes that the amatoxin molecule can be modified in the dihydroxyisoleucine residue without disruption of binding to the RNA polymerase.
按照维兰德和法尔迈尔（1）的方法操作后，对α-鹅膏蕈碱进行10⁻⁴裂解，但不预先对色氨酸残基的6'-羟基进行保护性甲基化，可得到产率为45%的α-鹅膏蕈碱醛。发现该醛对黑腹果蝇和小麦胚芽RNA聚合酶II的Ki值分别为3.0和12 μM。该值比母体α-鹅膏蕈碱大约高100倍。在甲醇、乙腈或二甲基亚砜中用2,4-二硝基苯肼处理α-鹅膏蕈碱醛，得到三种产物。其中两种不含2,4-二硝基苯基部分，对小麦胚芽RNA聚合酶II的Ki值分别为3.3和0.26 μM（α-鹅膏蕈碱的Ki值为0.09 μM），分别占输入的α-鹅膏蕈碱醛的30 - 60%和3%。无论反应条件如何，α-鹅膏蕈碱-2,4-二硝基苯腙的回收率均低于10%，且对小麦胚芽RNA聚合酶II的Ki值为0.26 μM。这种苯腙表明，鹅膏毒素分子可以在二羟基异亮氨酸残基处进行修饰，而不会破坏与RNA聚合酶的结合。
