@article {45763,
	title = {Cyclization mechanism of phomopsene synthase: mass spectrometry based analysis of various site-specifically labeled terpenes},
	journal = {Journal of Antibiotics},
	volume = {70},
	year = {2017},
	month = {MAY},
	pages = {632-638},
	type = {Article},
	abstract = {<p>Elucidation of the cyclization mechanism catalyzed by terpene synthases is important for the rational engineering of terpene cyclases. We developed a chemoenzymatic method for the synthesis of systematically deuterium-labeled geranylgeranyl diphosphate ( GGPP), starting from site-specifically deuterium-labeled isopentenyl diphosphates (IPPs) using IPP isomerase and three prenyltransferases. We examined the cyclization mechanism of tetracyclic diterpene phomopsene with phomopsene synthase. A detailed EI-MS analysis of phomopsene labeled at various positions allowed us to propose the structures corresponding to the most intense peaks, and thus elucidate a cyclization mechanism involving double 1,2-alkyl shifts and a 1,2-hydride shift via a dolabelladien-15-yl cation. Our study demonstrated that this newly developed method is highly sensitive and provides sufficient information for a reliable assignment of the structures of fragmented ions.</p>},
	issn = {0021-8820},
	doi = {10.1038/ja.2017.27},
	author = {Shinde, Sandip S. and Minami, Atsushi and Chen, Zhi and Tokiwano, Tetsuo and Toyomasu, Tomonobu and Kato, Nobuo and Sassa, Takeshi and Oikawa, Hideaki}
}
@article {44469,
	title = {Enzymatic formation of a skipped methyl-substituted octaprenyl side chain of longestin (KS-505a): involvement of homo-IPP as a common extender unit},
	journal = {Angewandte Chemie},
	volume = {57},
	year = {2018},
	month = {MAY},
	pages = {6629-6632},
	type = {Article},
	abstract = {<p>Longestin (KS-505a), a specific inhibitor of phosphodiesterase, is a meroterpenoid that consists of a unique octacyclic terpene skeleton with branched methyl groups at unusual positions (C1 and C12). The biochemical analysis of Lon23, a methyltransferase involved in the biosynthesis of longestin, demonstrated that methylation of IPP afforded 3Z-3-methyl IPP. This compound as well as IPP was selectively accepted as extender units by Lon22, a geranylgeranyl diphosphate (GGPP) synthase homolog, to yield dimethylated GGPP (dmGGPP). Absolute configuration of dmGGPP was determined to be (4R, 12R) by degradation and chiral GC analysis. These findings led us to propose key steps of the biosynthetic pathway of the unusual homoterpenoid longestin.</p>},
	doi = {10.1002/ange.201802116},
	author = {Taro Ozaki and Shinde, Sandip S. and Gao, Lei and Okuizumi, Ryo and Liu, Chengwei and Ogasawara, Yasushi and Lei, Xiaoguang and Dairi, Tohru and Minami, Atsushi and Oikawa, Hideaki}
}
