SEK-4b

• 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: SEK-4b
• 英文别名: SEK4b；2,7-dihydroxy-2-[(6-hydroxy-4-oxopyran-2-yl)methyl]-5-methyl-3H-chromen-4-one
• 化学式: C₁₆H₁₄O₇
• 分子量: 318.283
• InChiKey: UPCIFQHZBUREPV-UHFFFAOYSA-N

计算性质

• 辛醇/水分配系数(LogP)：
  1.26
• 重原子数：
  23.0
• 可旋转键数：
  2.0
• 环数：
  3.0
• sp3杂化的碳原子比例：
  0.25
• 拓扑面积：
  117.2
• 氢给体数：
  3.0
• 氢受体数：
  7.0

反应信息

• 作为产物：
  描述：

  S-乙酰乙酰基辅酶a 在 Streptomyces coelicolor actinorhodin polyketide synthase holo-acyl carrier protein C₁₇S mutant 、 Streptomyces coelicolor recombinant actinorhodin ketosynthase type II 、 5’-三磷酸腺苷 作用下， 以 aq. phosphate buffer 为溶剂， 以5.629E-10 mol的产率得到SEK-4
  参考文献：
  名称：

  Stabilization and enhanced reactivity of actinorhodin polyketide synthase minimal complex in polymer–nucleotide coacervate droplets

  摘要：

  在低离子强度和高离子强度条件下，通过将产荚膜多酮合酶的最小复合体分割到凝聚液滴中，能够提高旁路多酮产物的产量。

  DOI：

  10.1039/c2cc36533b

文献信息

• The Streptomyces glaucescens tcmKL polyketide synthase and tcmN polyketide cyclase genes govern the size and shape of aromatic polyketides
  作者：B. Shen、R. G. Summers、E. Wendt-Pienkowski、C. R. Hutchinson

  DOI：10.1021/ja00131a002

  日期：1995.7

  large and diverse family of secondary metabolites found in bacteria, fungi, and plants.’ Many of them are clinically valuable antibiotics or chemotherapeutic agents or have other useful pharmacological activities (immunosuppressive, antiparasitic, insecticidal, etc).2 Ever since Birch3 outlined his “acetate hypothesis” in the early 1950s that polyketides could be biosynthetically derived from short fatty

  通过在各种突变体或异源宿主中组合表达四烯霉素 (tcm) 和放线菌素 (act) 聚酮合酶基因的成分，分析了 I1 型聚酮合酶的机制。重组生物体产生的代谢物的结构分析为剖析 II 型 PKS 的各个成分的功能提供了证据。与包含 tcmK 和 actl-ORF2 或 actl-ORF1 和 tcmL 基因的 S. glaucescens TcmK 和 TcmL 突变体和构建体的互补研究表明，编码 j3-酮酰基 1:酰基载体蛋白合酶和链长因子的异源基因对通常是（但并非总是）不起作用。从带有 actl-ORF1、actl-ORF2 和 tcmM (pWHM766) 或 tcd、actl-ORF1、actl-ORF2 和 tcmM (pWHM768) 的菌株中分离出八酮化合物 6 和 7，来自带有 tcmK、tcmL 和 tcmM (pELE37) 或 tcd 、tcmK、tcmL 和 tcmM (pWHM731)
• Insight into the Molecular Basis of Aromatic Polyketide Cyclization: Crystal Structure and in Vitro Characterization of WhiE-ORFVI
  作者：Ming-Yue Lee、Brian D. Ames、Shiou-Chuan Tsai

  DOI：10.1021/bi201705q

  日期：2012.4.10

  Aromatic polyketides are biologically active natural products. Many important pharmaceuticals are derived from aromatic polyketides. Especially important in aromatic polyketide biosynthesis is the regiospecific cyclization of a linear, preassembled polyketide chain catalyzed by aromatase/cyclase (ARO/CYC), which serves as a key control point in aromatic ring formation. How different ARO/CYCs promote different cyclization patterns is not well understood. The whiE locus of Streptomyces coelicolor A3(2) is responsible for the biosynthesis of an aromatic polyketide precursor to the gray spore pigment. The WhiE ARO/CYC catalyzes the regiospecific C9-C14 and C7-C16 cyclization and aromatization of a 24-carbon polyketide chain. WhiE ARO/CYC shares a high degree of similarity to another nonreducing PKS ARO/CYC, TcmN ARO/CYC. This paper presents the apo crystal structure of WhiE ARO/CYC, and cocrystal structures of WhiE and TcmN ARO/CYCs bound with polycyclic aromatic compounds that mimic the respective ARO/CYC products. Site-directed mutagenesis coupled with in vitro PKS reconstitution assays was used to characterize the interior pocket residues of WhiE ARO/CYC. The results confirmed that the Interior pocket of ARO/CYCs is a critical determinant of polyketide cyclization specificity. A unified ARO/CYC-mediated cyclization mechanism is proposed on the basis of these structural and functional results.