(Z)-2-methyl-4,6-dioxohept-2-enedioic acid | 75164-76-0

• 分子结构分类: 有机化合物 - 有机酸及其衍生物 - 酮酸及其衍生物
• 英文名称: (Z)-2-methyl-4,6-dioxohept-2-enedioic acid
• CAS: 75164-76-0
• 化学式: C₈H₈O₆
• 分子量: 200.148
• InChiKey: FLEYITPUELIUDL-RQOWECAXSA-N

计算性质

• 辛醇/水分配系数(LogP)：
  -0.3
• 重原子数：
  14
• 可旋转键数：
  5
• 环数：
  0.0
• sp3杂化的碳原子比例：
  0.25
• 拓扑面积：
  109
• 氢给体数：
  2
• 氢受体数：
  6

反应信息

• 作为产物：
  描述：

  2,6-二甲基-1,4-苯二酚 在 2,6-dichlorohydroquinone 1,2-dioxygenase 作用下， 生成 (Z)-2-methyl-4,6-dioxohept-2-enedioic acid
  参考文献：
  名称：

  Substrate Specificity of Sphingobium chlorophenolicum 2,6-Dichlorohydroquinone 1,2-Dioxygenase

  摘要：

  PcpA is an aromatic ring-cleaving dioxygenase that is homologous to the well-characterized Fe(II)-dependent catechol, extradiol dioxygenases. This enzyme catalyzes the oxidative cleavage of 2,6-dichlorohydroquinone in the catabolism of pentachlorophenol by Sphingobium chlorophenolicum ATCC 39723. H-1 NMR and steady-state kinetics were used to determine the regiospecificity of ring cleavage and the substrate specificity of the enzyme. PcpA exhibits a high degree of substrate specificity for 2,6-disubstituted hydroquinones, with halogens greatly preferred at those positions. Notably, the k(cat)(app)/K-mA(app) of 2,6-dichlorohydroquinone is similar to 40-fold higher than that of 2,6-dimethylhydroquinone. The asymmetric substrate 2-chloro-6-methylhydroquinone yields a mixture of 1,2- and 1,6-cleavage products. These two modes of cleavage have different K-mO(app) values (21 and 260 mu M, respectively), consistent with a mechanism in which the substrate binds in two catalytically productive orientations. In contrast, monosubstituted hydroquinones show a limited amount of ring cleavage but rapidly inactivate the enzyme in an O-2-dependent fashion, suggesting that oxidation of the Fe(II) may be the cause. Potent inhibitors of PcpA include ortho-disubstituted phenols and 3-bromocatechol. 2,6-Dibromophenol is the strongest competitive inhibitor, consistent with PcpA's substrate specificity. Several factors that could yield this specificity for halogen substituents are discussed. Interestingly, 3-bromocatechol also inactivates the enzyme, while 2,6-dihalophenols do not, indicating a requirement for two hydroxyl groups for ring cleavage and for enzyme inactivation. These results provide mechanistic insights into the hydroquinone dioxygenases.

  DOI：

  10.1021/bi200855m

文献信息

• Substrate Specificity of <i>Sphingobium chlorophenolicum</i> 2,6-Dichlorohydroquinone 1,2-Dioxygenase
  作者：Timothy E. Machonkin、Amy E. Doerner

  DOI：10.1021/bi200855m

  日期：2011.10.18

  PcpA is an aromatic ring-cleaving dioxygenase that is homologous to the well-characterized Fe(II)-dependent catechol, extradiol dioxygenases. This enzyme catalyzes the oxidative cleavage of 2,6-dichlorohydroquinone in the catabolism of pentachlorophenol by Sphingobium chlorophenolicum ATCC 39723. H-1 NMR and steady-state kinetics were used to determine the regiospecificity of ring cleavage and the substrate specificity of the enzyme. PcpA exhibits a high degree of substrate specificity for 2,6-disubstituted hydroquinones, with halogens greatly preferred at those positions. Notably, the k(cat)(app)/K-mA(app) of 2,6-dichlorohydroquinone is similar to 40-fold higher than that of 2,6-dimethylhydroquinone. The asymmetric substrate 2-chloro-6-methylhydroquinone yields a mixture of 1,2- and 1,6-cleavage products. These two modes of cleavage have different K-mO(app) values (21 and 260 mu M, respectively), consistent with a mechanism in which the substrate binds in two catalytically productive orientations. In contrast, monosubstituted hydroquinones show a limited amount of ring cleavage but rapidly inactivate the enzyme in an O-2-dependent fashion, suggesting that oxidation of the Fe(II) may be the cause. Potent inhibitors of PcpA include ortho-disubstituted phenols and 3-bromocatechol. 2,6-Dibromophenol is the strongest competitive inhibitor, consistent with PcpA's substrate specificity. Several factors that could yield this specificity for halogen substituents are discussed. Interestingly, 3-bromocatechol also inactivates the enzyme, while 2,6-dihalophenols do not, indicating a requirement for two hydroxyl groups for ring cleavage and for enzyme inactivation. These results provide mechanistic insights into the hydroquinone dioxygenases.