BIOSYNTHESIS OF PARAHERQUAMIDES & BREVIANAMIDES

SIR提供[1_13C，90%脯氨酸; 15g [1_13C，98%]色氨酸; .35g 【U_13C，？9]异亮氨酸;. 159 g对乙酰甲喹酰胺是复杂的， 七环，有毒的霉菌代谢物，从各种青霉菌中分离 短藤酰胺A和B是结构上相关的天然产物 其显示出有效的杀虫活性。 所述灯盏花素酰胺还 由青霉属霉菌产生。 我们正在追求 鉴定一种新的酶机制， 在构建双环[2.2.21核的 brevianamides/paraherquamides。 我们已经获得了令人信服的 实验证明这种独特的星环系统 通过酶催化的分子内Diels-Alder 环加成反应 尽管它广泛用于合成 在有机化学中，Diels-Alder环加成反应不 在自然界中经常发生，没有一个记录在案的 一种酶催化这种最普遍的合成酶的例子 成环反应 青霉菌产生的 brevianamides/paraherquamides可能是一种罕见的，但至关重要的 这是狄尔斯-阿尔德酶存在的一个例子。 一个最 该项目的重要目标是描述这种罕见的 催化的生物合成结构 使用提供给 我们通过SIR，我们已经确定， paraherquamide衍生自L-He，而不是通过SAM-甲基化 脯氨酸 此外，我们最近发现，L-色氨酸是 二氧杂环庚烯羟吲哚的生物合成前体， 对海夸酰胺和N-甲基衍生自L-Met。 我们 先前已经合成了氚化哌嗪二酮， 证明这种物质有效地结合到 短藤酰胺A和B。我们目前的努力方向是 合成含13 C标记的β-甲基脯氨酸衍生物， 进行生物合成喂养实验 我们希望确定 L-Ile转化为β-甲基脯氨酸的途径， 从那里得到paraherquamide A。

The SIR provided [1_13C, 90%proline; . 15g [1_13C, 98%]tryp; .35g [U_13C, ?9]isoleucine;. 159g The paraherquamides are complex, heptacyclic, toxic mold metabolites, isolated from various Penicillium sp.The brevianamides A and B are structurally related natural products that display potent insecticidal activity. The brevianamides are also produced by Penicillium sp. molds. We are pursuing the identification of a new mechanistic class of enzymes that are involved in constructing the bicyclo [2.2.21 nucleus of the brevianamides/paraherquamides. We have obtained compelling experimental evidence that this unique ring system is very possible constructed via an enzyme-catalyzed intramolecular Diels-Alder cycloaddition reaction. Despite its widespread use in synthetic organic chemistry, the Diels-Alder cycloaddition reaction does not occur frequently in nature and there is not a single documented example of an enzyme that catalyzes this most ubiquitous synthetic ring-forming reaction. The Penicillium sp. that produces the brevianamides/paraherquamides may be a rare, but vitally important example of the existence of Diels-Alderases. One of the most significant objectives of this project is to characterize this rare catalyzed, biosynthetic construction. Using amino acids provided to us by the SIR, we have established that the 0-methyl proline ring in paraherquamide is derived from L-He and not via the SAM-methylation of L-proline. In addition , we have recently shown that L-tryptophan is the biosynthetic precursor to the dioxepin oxindole half of paraherquamide and that the N-methyl group is derived from L-Met. We have previously synthesized the tritiated piperazinedione and have demonstrated that this substance is efficiently incorporated into brevianamides A and B. Our current efforts are directed toward synthesizing the P-methyloproline derivatives containing 13C-labels for biosynthetic feeding experiments. We wish to establish the exact pathway by which the L-Ile is converted into P-methyloproline and thence, into paraherquamide A.