Institute for Microbiology, University of Stuttgart, Stuttgart, Germany.
Appl Environ Microbiol. 2011 Jun;77(12):3905-15. doi: 10.1128/AEM.00300-11. Epub 2011 Apr 29.
Hopanoids and sterols are members of a large group of cyclic triterpenoic compounds that have important functions in many prokaryotic and eukaryotic organisms. They are biochemically synthesized from linear precursors (squalene, 2,3-oxidosqualene) in only one enzymatic step that is catalyzed by squalene-hopene cyclase (SHC) or oxidosqualene cyclase (OSC). SHCs and OSCs are related in amino acid sequences and probably are derived from a common ancestor. The SHC reaction requires the formation of five ring structures, 13 covalent bonds, and nine stereo centers and therefore is one of the most complex one-step enzymatic reactions. We summarize the knowledge of the properties of triterpene cyclases and details of the reaction mechanism of Alicyclobacillus acidocaldarius SHC. Properties of other SHCs are included.
藿烷类化合物和甾醇是一大类环状三萜类化合物的成员，它们在许多原核和真核生物中具有重要功能。它们仅通过一个酶促步骤从线性前体（鲨烯、2,3-氧化鲨烯）生物合成，该步骤由鲨烯-霍烯环化酶（SHC）或氧化鲨烯环化酶（OSC）催化。SHC 和 OSC 在氨基酸序列上相关，可能源自共同的祖先。SHC 反应需要形成五个环结构、13 个共价键和 9 个立体中心，因此是最复杂的一步酶促反应之一。我们总结了三萜环化酶的性质和 Alicyclobacillus acidocaldarius SHC 反应机制的详细信息。还包括其他 SHC 的性质。
