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Enancjoselektywna enzymatyczna desymetryzacja katalizowana oksydoreduktazami. Reakcje utleniania. Część 2

Karczmarska-Wódzka A., Kołodziejska R., Tafelska-Kaczmarek A., Studzińska R., Wróblewski M., Augustyńska B.

Wiadomości Chemiczne

2015

[Z] 69, 1-2

53--64

In continuation of our work, we herein describe next enzyme classes applied for oxidation reaction. Dioxygenases, oxidases, and peroxidases are successfully used in the synthesis of desymmetrization products with high yields and enantiomeric excesses. Aromatic dioxygenases, such as toluene dioxygenase (TDO), naphthalene dioxygenase (NDO), and biphenyl dioxygenase (BPDO) found in the prokaryotic microorganisms are enzymes belonging to the dioxygenase class and are the most commonly used in organic synthesis. The α-oxidation of various fatty acids in the presence of an α-oxidase from germinating peas is one of the few examples of oxidases application in asymmetric organic synthesis. The intermediary α-hydroxyperoxyacids can undergo two competing reactions: decarboxylation of the corresponding aldehydes or reduction to the (R)-2-hydroxy acids. In order to eliminate the competitive decarboxylation reaction tin(II) chloride is used as an in situ reducing agent. Peroxidases are the redox enzymes found in various sources such as animals, plants, and microorganisms. Due to the fact that, in contrast to monooxygenases, no additional cofactors are required, peroxidases are highly attractive for the preparative biotransformation. Oxidation reactions catalyzed by (halo)peroxydases are also often used in organic synthesis. N-Oxidation of amines, for instance, leads to the formation of the corresponding aliphatic N-oxides, aromatic nitro-, or nitrosocompounds. From a preparative synthesis standpoint, however, sulfoxidation of thioether is important since it was proven to proceed in a highly stereo- and enantioselective manner. Furthermore, depending on the source of haloperoxidase, chiral sulfoxides of opposite configurations can be obtained.

Współczesne metody badawcze w określaniu struktur dioksygenaz intradiolowych

Wojcieszyńska D., Hupert-Kocurek K., Sitnik M., Guzik U.

Chemik

2012

Vol. 66, nr 12

1346--1351

Dioksygenazy intradiolowe są kluczowymi enzymami szlaku orto rozkładu związków aromatycznych. Ze względu na rodzaj intermediatu, którego pierścień rozszczepiają, enzymy te zaliczane są do trzech klas. Obecnie, dzięki zastosowaniu nowoczesnych metod badawczych takich jak: krystalografia rentgenowska, spektrometria mas, spektroskopia elektronowego rezonansu paramagnetycznego oraz spektroskopia rentgenowska, możliwe jest dokładne poznanie nie tylko ich budowy przestrzennej, ale również wyjaśnienie sposobu wiązania się substratu z ligandami centrum aktywnego oraz poznanie mechanizmu katalizy.

Intradiol dioxygenases are essential enzymes of ortho pathway involved in the decomposition of aromatic compounds. Enzymes are grouped into three classes on account of a type of the intermediate whose ring they cleave. Nowadays, the application of such modern research methods as X-ray crystallography, mass spectrometry, electron paramagnetic resonance spectroscopy, and X-ray spectroscopy creates possibilities for the thorough understanding of their spatial structure as well as for explaining the way of substrate binding with ligands in the active site and learning the catalysis mechanism.