Functional characterization of a stereospecific diol dehydrogenase, FucO, from Escherichia coli: Substrate specificity, pH dependence, kinetic isotope effects and influence of solvent viscosity
作者:Cecilia Blikstad、Mikael Widersten
DOI:10.1016/j.molcatb.2010.04.010
日期:2010.9
oxidoreductase, from Escherichiacoli is involved in the anaerobic catabolic metabolism of l-fucose and l-rhamnose, catalyzing the interconversion of lactaldehyde to propanediol. The enzyme is specific for the S-enantiomers of the diol and aldehyde suggesting stereospecificity in catalysis. We have studied the enzyme kinetics of FucO with a spectrum of putative alcohol and aldehyde substrates to map the substrate
来自大肠杆菌的FucO,(S)-1,2-丙二醇氧化还原酶参与1-岩藻糖和1-鼠李糖的厌氧分解代谢,催化乳醛向丙二醇的相互转化。该酶对S具有特异性-二醇和醛的β-对映异构体表明在催化中具有立体特异性。我们已经研究了FucO的酶动力学与一系列推定的醇和醛底物,以绘制底物特异性空间。此外,为了更详细地分析动力学机理,还分析了催化剂的pH依赖性,氢化物转移的立体化学,氢化物转移的氘动力学同位素效应和溶剂粘度增加的效应。这项研究的结果可以总结如下:FucO具有高度立体定向性,S的E值最高,为320-1,2-丙二醇的对映体。该酶对伯醇的氧化具有严格的区域特异性。该酶更喜欢短链(2-4个碳原子)的底物,并且不作用于体积较大的化合物,例如苯基取代的醇。FucO是一种“ A端”脱氢酶,可将NADH的原R-氢转移至醛底物。k cat和k cat的氘KIE / K M分别为1.9和4.2,说明氢化物转移是部分限
Stereochemical Outcome at Four Stereogenic Centers during Conversion of Prephenate to Tetrahydrotyrosine by BacABGF in the Bacilysin Pathway
作者:Jared B. Parker、Christopher T. Walsh
DOI:10.1021/bi3006362
日期:2012.7.17
NADH-utilizing BacG then catalyzes a conjugatereduction, adding a pro-S hydride equivalent to C4 to yield tetrahydrohydroxyphenylpyruvate (H4HPP), a transamination away (via BacF) from 2S-H4Tyr. Incubations of the pathway enzymes in D2O yield deuterium incorporation at C8 from BacA and then C9 from BacB action. By 1H NMR analysis of samples of H4Tyr, the stereochemistry at C4, C8, and C9 can be assigned
Stereochemistry of reduction of the endocyclic double bond of (−)-carvone with the enzyme preparation from cultured cells of Nicotiana tabacum
作者:Toshifumi Hirata、Yixiong Tang、Kuniko Okano、Takayuki Suga
DOI:10.1016/0031-9422(89)80341-3
日期:——
endocyclic double bond; (ii) the reduction occurs stereospecifically by anti addition of hydrogen from the si face at C-1 and the re face at C-6 of carvone, resulting in the formation of (1 R , 4 R )-(+)-dihydrocarvone; (iii) the hydrogen atoms participating in the enzymatic reduction at C-1 and C-6 originate from the medium and the pro -4 R hydrogen of NADH, respectively.
摘要 通过2 H NMR和质谱研究了用来自烟草培养细胞的酶制剂还原(4 R )-(-)-香芹酮的环内CC双键的立体化学。发现:(i)酶制剂仅区域选择性地还原环内双键;(ii) 通过从香芹酮的 C-1 处和 C-6 处的反加氢反加成氢而立体定向地发生还原,导致形成 (1 R , 4 R )-(+)-二氢香芹酮;(iii) 参与 C-1 和 C-6 酶促还原的氢原子分别来自介质和 NADH 的 pro -4 R 氢。
Oxidation of NADH involving rate-limiting one-electron transfer
作者:Brian W. Carlson、Larry L. Miller、P. Neta、Jan Grodkowski
DOI:10.1021/ja00335a062
日期:1984.11
Cinetique et mecanisme de l'oxydation de NADH par l'ion ferroceniumyle et quelques derives substitues de cet ion dans le propanol-1 aqueux
Cinetique et mecanisme de l'oxydation de NADH par l'ion ferroceniumyle et quelques 衍生替代物 de cet ion dans le propanol-1 aqueux
Biosynthesis of the thiamin pyrimidine: the reconstitution of a remarkable rearrangement reaction
作者:Brian G. Lawhorn、Ryan A. Mehl、Tadhg P. Begley
DOI:10.1039/b405429f
日期:——
The conversion of 5-aminoimidazole ribonucleotide (AIR) into 4-amino-2-methyl-5-hydroxymethylpyrimidine (HMP) is a fascinating reaction on the thiamin biosynthetic pathway in bacteria and is probably the most complex unresolved rearrangement in primary metabolism. We have successfully reconstituted this reaction in a cell-free system. The E. coli thiC gene product and an additional unidentified E. coli protein are required for the reaction. In addition, SAM and nicotinamide cofactors are required for full activity. Labeling studies to determine the origin of most of the atoms in the pyrimidine are described. Based on these studies, a new mechanism for HMP formation is proposed.