Weibel D B, Oldham N J, Feld B, Glombitza G, Dettner K, Boland W
Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14850, USA.
Insect Biochem Mol Biol. 2001 Apr 27;31(6-7):583-91. doi: 10.1016/s0965-1748(00)00163-6.
The biosynthesis of chrysomelidial and plagiodial was studied in the rove beetle subtribe Philonthina (Staphylinidae). Glandular homogenates were found to convert synthetic (2E,6E)-[trideuteromethyl-5,5-(2)H(5)]octa-2,6-diene-1,8-diol (10) into nor-chrysomelidial (14) and nor-plagiodial (13). The overall transformation requires; i) oxidation of the substrate at C(1) and C(8), ii) cyclization of the resulting dialdehyde to nor-plagiodial followed by iii) isomerization to give nor-chrysomelidial. The oxidase requires molecular oxygen as a cofactor and operates with removal of the pro-R hydrogen from C(1) and C(8) of synthetic (1R,8R,2E,6E)-[1,8-(2)H(2)]-2,6-dimethyl-octa-2,6-diene-1,8-diol (15), producing a dialdehyde along with H(2)O(2). Unlike enzymes from iridoid-producing leaf beetle larvae, the Philonthus enzyme is able to oxidize saturated substrates such as citronellol. Crude protein extracts prepared from Philonthus glands by ammonium sulfate precipitation, were found to produce hydrogen peroxide at a rate of 0.085+/-0.003 ng H(2)O(2) (ng protein)(-1) hr(-1) with nerol as an oxidase substrate. The cyclase operates with opposite stereochemistry to the enzyme(s) from Phaedon cochleariae and other herbivorous leaf beetles, specifically removing the C(5)-H(R) hydrogen atom from (4R,5S,2E,6E)-[4,5-(2)H(2)]-2-methyl-octa-2,6-diene-1,8-diol (17). These findings have enabled us to construct a detailed account of iridoid biosynthesis in rove beetles, which resembles the biosynthetic route in leaf beetle larvae, but exhibits distinct stereochemical differences.
在隐翅虫亚族Philonthina（隐翅虫科）中研究了 Chrysomelidial 和 Plagiodial 的生物合成。发现腺体匀浆能将合成的(2E,6E)-[三氘甲基 - 5,5-(2)H(5)]辛 - 2,6 - 二烯 - 1,8 - 二醇(10)转化为降 - Chrysomelidial(14)和降 - Plagiodial(13)。整个转化过程需要：i) 底物在 C(1)和 C(8)处氧化；ii) 所得二醛环化生成降 - Plagiodial，随后 iii) 异构化生成降 - Chrysomelidial。氧化酶以分子氧作为辅因子，作用于从合成的(1R,8R,2E,6E)-[1,8-(2)H(2)] - 2,6 - 二甲基 - 辛 - 2,6 - 二烯 - 1,8 - 二醇(15)的 C(1)和 C(8)去除前 - R 氢，生成二醛和 H₂O₂。与来自产生环烯醚萜的叶甲幼虫的酶不同，Philonthus 酶能够氧化饱和底物，如香茅醇。通过硫酸铵沉淀从 Philonthus 腺体制备的粗蛋白提取物，以橙花醇作为氧化酶底物时，产生过氧化氢的速率为 0.085±0.003 ng H₂O₂(ng 蛋白)⁻¹ hr⁻¹。环化酶的立体化学作用与来自 Phaedon cochleariae 和其他食草叶甲的酶相反，具体是从(4R,5S,2E,6E)-[4,5-(2)H(2)] - 2 - 甲基 - 辛 - 2,6 - 二烯 - 1,8 - 二醇(17)中去除 C(5)-H(R)氢原子。这些发现使我们能够构建隐翅虫中环烯醚萜生物合成的详细过程，其类似于叶甲幼虫中的生物合成途径，但表现出明显的立体化学差异。
