BIOSYNTHESIS OF ASCARIDOLE - IODIDE PEROXIDASE-CATALYZED SYNTHESIS OF A MONOTERPENE ENDOPEROXIDE IN SOLUBLE EXTRACTS OF CHENOPODIUM-AMBROSIOIDES FRUIT
BIOSYNTHESIS OF ASCARIDOLE - IODIDE PEROXIDASE-CATALYZED SYNTHESIS OF A MONOTERPENE ENDOPEROXIDE IN SOLUBLE EXTRACTS OF CHENOPODIUM-AMBROSIOIDES FRUIT
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DOI：
10.1016/0003-9861(84)90274-1
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发表时间：
1984-01-01
影响因子：
3.9
通讯作者：
CROTEAU, R
中科院分区：
文献类型：
--
作者：
JOHNSON, MA;CROTEAU, R
蛔虫素是一种具有驱虫特性的不对称单萜内过氧化物，作为主要成分（60-80%）存在于美洲虫籽果实（土荆芥：藜科）的挥发油中，并作为次要成分存在于博多树（Peumus boldus; Monimiaceae）的叶袋油中。天然存在的蛔虫素和几种合成衍生物的光学活性和色谱分离的测定表明，无论是蚯蚓和boldo产生蛔虫素的外消旋形式。从共轭对称二烯α-环己二烯生物合成蛔虫素松油烯（蚯蚓籽油的主要成分）由从C.土荆芥果实和叶。通过毛细管气相色谱和质谱分析证实了酶促合成的产物，该产物也是外消旋的。最佳酶活性发生在pH 4.0，在2.5 mM H2 O2和1 mM NaI的存在下。可溶性酶提取物通过Sephacryl S-300和Sephadex G-100上的凝胶过滤进行分级;它们由高MW过氧化物酶组分（MW > 1，000，000，总活性的30%）和具有62，000和45，000的表观MW的2种其它过氧化物酶种类（主要组分）组成。过氧化物酶活性仅在高碘酸盐处理后才对蛋白水解破坏敏感，表明酶与多糖物质相关。从α-聚天冬氨酸生物合成蛔虫素萜品烯被氰化物、过氧化氢酶和还原剂抑制，但不被捕获超氧化物或淬灭单线态氧的化合物抑制。提出了由过氧化物酶产生的I+引发的过氧化物转移反应用于转化α-萜品烯到蛔虫素。
Ascaridole, an asymmetric monoterpene endoperoxide with anthelmintic properties, occurs as a major constituent (60-80%) in the volatile oil of American wormseed fruit (Chenopodium ambrosioides: Chenopodiaceae), and as a lesser component in the leaf pocket oil of the boldo tree (Peumus boldus; Monimiaceae). Determination of optical activity and chromatographic resolution of naturally occurring ascaridole and several synthetic derivatives showed that both wormseed and boldo produce ascaridole in racemic form. The biosynthesis of ascaridole from the conjugated, symmetrical diene .alpha.-terpinene (a major component of the oil from wormseed) is catalyzed by a soluble iodide peroxidase isolated from homogenates of C. ambrosioides fruit and leaves. The enzymatic synthesis of ascaridole was confirmed by capillary GLC and mass spectrometry of the product, which is also racemic. Optimal enzymatic activity occurred at pH 4.0, in the presence of 2.5 mM H2O2 and 1 mM NaI. Soluble enzyme extracts were fractionated by gel filtration on both Sephacryl S-300 and Sephadex G-100; they consist of a high-MW peroxidase component (MW > 1,000,000, 30% of total activity) and 2 other peroxidase species having apparent MW of 62,000 and 45,000 (major component). Peroxidase activity was susceptible to proteolytic destruction only after periodate treatment, suggesting an association of the enzyme(s) with polysaccharide material. Ascaridole biosynthesis from .alpha.-terpinene was inhibited by cyanide, catalase, and reducing agents, but not by compounds that trap superoxide or quench singlet oxygen. A peroxide transfer reaction initiated by peroxidase-generated I+ is proposed for the conversion of .alpha.-terpinene to ascaridole.