SEK4b

• 分子结构分类: 有机化合物 - 有机杂环化合物 - 苯并吡喃
• 英文名称: SEK4b
• 英文别名: 2,7-dihydroxy-2-[(4-hydroxy-6-oxopyran-2-yl)methyl]-5-methyl-3H-chromen-4-one
• 化学式: C₁₆H₁₄O₇
• 分子量: 318.283
• InChiKey: PCNFFWATXFRKOF-UHFFFAOYSA-N

计算性质

• 辛醇/水分配系数(LogP)：
  0.9
• 重原子数：
  23
• 可旋转键数：
  2
• 环数：
  3.0
• sp3杂化的碳原子比例：
  0.25
• 拓扑面积：
  113
• 氢给体数：
  3
• 氢受体数：
  7

反应信息

• 作为产物：
  描述：

  丙二酰辅酶A-钠盐 在 potassium phosphate buffer 、 乙二胺四乙酸 、 wild-type octaketide synthase 作用下， 反应 18.0h， 生成 SEK4b 、 SEK4
  参考文献：
  名称：

  植物聚酮化合物的工程生物合成：生产八肽的植物 III 型聚酮化合物合成酶中的链长控制

  摘要：

  III 型聚酮化合物合酶 (PKS) 的查尔酮合酶 (CHS) 超家族产生多种具有显着结构多样性和生物活性的植物次级代谢产物（例如查耳酮、芪、二苯甲酮、丙烯、间苯三酚、间苯二酚、吡喃酮和色酮）。在这里，我们描述了一种来自芦荟（Aloe arborescens）的产生八酮化合物的新型植物特异性 III 型 PKS，与其他植物 CHS 超家族酶具有 50-60% 的氨基酸序列同一性。在大肠杆菌中表达的重组酶催化丙二酰辅酶 A 的七次连续脱羧缩合反应，产生芳香族八酮化合物 SEK4 和 SEK4b，这是已知由结构简单的 III 型 PKS 合成的最长的聚酮化合物。令人惊讶的是，定点诱变显示单个残基 Gly207（对应于 CHS' s 活性位点 Thr197) 决定了聚酮链长度和产品特异性。从小到大的取代（G207A、G207T、G207M、G207L、G207F 和 G207W）导致八酮化合物形

  DOI：

  10.1021/ja053945v

文献信息

• Production of Carminic Acid by Metabolically Engineered <i>Escherichia coli</i>
  作者：Dongsoo Yang、Woo Dae Jang、Sang Yup Lee

  DOI：10.1021/jacs.0c12406

  日期：2021.4.14

  Carminic acid is an aromatic polyketide found in scale insects (i.e., Dactylopius coccus) and is a widely used natural red colorant. It has long been produced by the cumbersome farming of insects followed by multistep purification processes. Thus, there has been much interest in producing carminic acid by the fermentation of engineered bacteria. Here we report the complete biosynthesis of carminic

  胭脂红酸是一种在介壳虫（即指藻）中发现的芳香族聚酮化合物，是一种广泛使用的天然红色着色剂。长期以来，它是通过繁琐的昆虫养殖和多步纯化过程生产的。因此，人们对通过工程细菌发酵生产胭脂红酸产生了很大的兴趣。在这里，我们报道了工程大肠杆菌中葡萄糖完全生物合成胭脂红酸的过程。我们首先优化了发光杆菌 ( Photorhabdus luminescens ) 的 II 型聚酮合酶机制，通过链霉菌(Streptomyces sp) 环化酶 ZhuI 和 ZhuJ 的共表达，能够高水平生产黄酮酮酸。 R1128。为了发现负责其余两个反应（羟基化和C-葡萄糖基化）的酶，通过测试报告执行类似反应的候选酶来进行生化反应分析。两种鉴定的酶，来自链霉菌的aklavinone 12-羟化酶（DnrF）和来自三花龙胆的C-葡萄糖基转移酶（GtCGT），分别可以成功地进行黄酮酸的羟基化和C-葡萄糖基化。然后，进行同源建模
• Enzymatic formation of an unnatural methylated triketide by plant type III polyketide synthases
  作者：Tsuyoshi Abe、Hisashi Noma、Hiroshi Noguchi、Ikuro Abe

  DOI：10.1016/j.tetlet.2006.10.012

  日期：2006.12

  Octaketide synthase, a novel plant-specific type III polyketide synthase from Aloe arborescens, efficiently accepted (2RS)-methylmalonyl-CoA as a sole substrate to produce 6-ethyl-4-hydroxy-3,5-dimethyl-2-pyrone. On the other hand, a tetraketide-producing chalcone synthase from Scutellaria baicalensis and a diketide-producing benzalacetone synthase from Rheum palmatum also yielded the unnatural methylated C-9 triketide pyrone as a single product by sequential decarboxylative condensations of three molecules of (2RS)-methylmalonyl-CoA. (c) 2006 Elsevier Ltd. All rights reserved.
• Enzymatic Formation of Unnatural Novel Chalcone, Stilbene, and Benzophenone Scaffolds by Plant Type III Polyketide Synthase
  作者：She-Po Shi、Kiyofumi Wanibuchi、Hiroyuki Morita、Kohei Endo、Hiroshi Noguchi、Ikuro Abe

  DOI：10.1021/ol802606w

  日期：2009.2.5

  A C-19 hexaketide stilbene and a C-21 heptaketide chalcone were synthesized by Aloe arborescens octaketide synthase (OKS), a plant-specific type III polyketide synthase (PKS). Remarkably, the C21 chalcone-forming activity was dramatically increased in a structure-guided OKS N222G mutant that produces a C-20 decaketide SEK15 from 10 molecules of malonyl-CoA. The findings suggested further strategies for production of unnatural polyketides by combination of the precursor-directed biosynthesis and the structure-guided engineering of type III PKS.
• Structure-Based Engineering of a Plant Type III Polyketide Synthase:  Formation of an Unnatural Nonaketide Naphthopyrone
  作者：Ikuro Abe、Hiroyuki Morita、Satoshi Oguro、Hisashi Noma、Kiyofumi Wanibuchi、Nobuo Kawahara、Yukihiro Goda、Hiroshi Noguchi、Toshiyuki Kohno

  DOI：10.1021/ja070375l

  日期：2007.5.1

  Pentaketide chromone synthase (PCS) from Aloe arborescens is a novel plant-specific type III polyketide synthase (PKS) that produces 5,7-dihydroxy-2-methylchromone from five molecules of malonyl-CoA. On the basis of the crystal structures of wild-type and M207G mutant PCS, the F80A/Y82A/M207G triple mutant was constructed and shown to produce an unnatural novel nonaketide naphthopyrone by sequential condensations of nine molecules of malonyl-CoA. This is the first demonstration of the formation of a nonaketide by the structurally simple type III PKS. A homology model predicted that the active-site cavity volume of the triple mutant is increased to 4 times that of the wild-type PCS.
• A Plant Type III Polyketide Synthase that Produces Pentaketide Chromone
  作者：Ikuro Abe、Yoriko Utsumi、Satoshi Oguro、Hiroyuki Morita、Yukie Sano、Hiroshi Noguchi

  DOI：10.1021/ja0431206

  日期：2005.2.1

  A novel plant-specific type III polyketide synthase (PKS) that catalyzes formation of a pentaketide chromone, 5,7-dihydroxy-2-methylchromone, from five molecules of malonyl-CoA, was cloned and sequenced from aloe (Aloe arborescens). Site-directed mutagenesis revealed that Met207 (corresponding to Thr197 in CHS) determines the polyketide chain length and the product specificity of the enzyme; remarkably, replacement of a single amino acid residue, Met207, with Gly yielded a mutant enzyme that efficiently produces aromatic octaketides, SEK4 and SEK4b, the products of the minimal PKS for actinorhodin (act from Streptomyces coelicolor), from eight molecules of malonyl-CoA. This provided new insights into the catalytic functions and specificities of the CHS-superfamily type III PKS enzymes.