Video Experimental Relacionado
Updated: Mar 30, 2026
08:57
Simultaneous Measurement of Superoxide/Hydrogen Peroxide and NADH Production by Flavin-containing Mitochondrial Dehydrogenases
Published on: February 24, 2018
10.6K
Formación de endoperoxidos por una enzima de hierro mononuclear no hemo dependiente del α-cetoglutarato
Wupeng Yan1, Heng Song2, Fuhang Song3
1Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas 78712, USA.
Nature
|November 3, 2015
Resumen
Los investigadores descubrieron el nuevo mecanismo de formación de endoperoxido por Aspergillus fumigatus fumitremorgin B endoperoxidasa (FtmOx1), una enzima de hierro no hemo. Un residuo de tirosina clave protege el sitio activo, dirigiendo la catálisis hacia la síntesis de endoperoxido en lugar de la hidroxilación.
Área de la Ciencia:
- La bioquímica
- Enzimología
- Biología estructural
Sus antecedentes:
- Los metabolitos secundarios que contienen peróxido ofrecen beneficios para la salud, pero sus mecanismos de biosíntesis son poco conocidos.
- La prostaglandina H sintasa es la única enzima biosintética endoperoxídica bien caracterizada, que utiliza un cofactor hemo.
- La Fumitremorgina B endoperoxidasa (FtmOx1) de Aspergillus fumigatus es una nueva enzima mononuclear no hemo de hierro dependiente del α-cetoglutarato que cataliza la formación de endoperoxidos.
Objetivo del estudio:
- Para aclarar los detalles mecánicos de la formación de endoperoxidos por FtmOx1.
- Investigar el papel de un residuo específico de tirosina (Y224) en la catálisis de FtmOx1.
- Caracterización de las especies radicales transitorias involucradas en la reacción enzimática.
Principales métodos:
- Cristalografía de rayos X de FtmOx1 y sus complejos binarios con α-cetoglutarato y fumitremorgina B.
- Mutagénesis dirigida al sitio del residuo Y224.
- Espectroscopia de absorción óptica de flujo detenido.
- Espectroscopia de resonancia paramagnética de electrones de congelación y apagado (EPR).
Principales resultados:
- Las estructuras cristalinas revelaron la unión de α-cetoglutarato al centro de hierro, con Y224 protegiendo el sitio de activación de oxígeno.
- La mutación de Y224 a alanina o fenilalanina desplazó la catálisis de la formación de endoperoxidos a la hidroxilación.
- Los análisis espectroscópicos proporcionaron evidencia de especies radicales transitorias durante la catálisis de FtmOx1.
Conclusiones:
- FtmOx1 emplea un mecanismo único para la formación de endoperoxidos, distinto de las enzimas conocidas que contienen hemo.
- El residuo Y224 juega un papel crítico en la selectividad del sustrato y en la dirección de la vía de reacción.
- El estudio revela una nueva vía enzimática que involucra radicales intermedios para la biosíntesis de endoperoxidos.
Videos de Conceptos Relacionados
01:43Electron Transport Chain: Complex III and IV
9.7K
During the electron transport chain, electrons from NADH and FADH2 are first transferred to complexes I and II, respectively. These two complexes then transfer the electrons to ubiquinol, which carries them further to complex III. Complex III passes the electrons across the intermembrane space to Cyt c, which carries them further to complex IV. Complex IV donates electrons to oxygen and reduces it to water. As electrons pass through complexes I, III, and IV, the energy released aids the pumping...
9.7K
01:24Peroxisomes
22.1K
Peroxisomes are specialized organelles present in fungi, plant, and animal cells. It can vary in number, size, morphology, and activity depending on the type of tissue and the nutritional state of the cell. For example, cells with active lipid metabolism, such as adipocytes, neurons, and hepatocytes, have more peroxisomes than other cells in the body. Besides their primary role in breaking down complex organic molecules, peroxisomes can also synthesize specific macromolecules and participate in...
22.1K
01:24Peroxisomes
1.9K
1.9K
02:04Oxidation of Alkenes: Anti Dihydroxylation with Peroxy Acids
8.1K
Diols are compounds with two hydroxyl groups. In addition to syn dihydroxylation, diols can also be synthesized through the process of anti dihydroxylation. The process involves treating an alkene with a peroxycarboxylic acid to form an epoxide. Epoxides are highly strained three-membered rings with oxygen and two carbons occupying the corners of an equilateral triangle. This step is followed by ring-opening of the epoxide in the presence of an aqueous acid to give a trans diol.
8.1K
01:15Pyruvate Oxidation
171.6K
After glycolysis, the charged pyruvate molecules enter the mitochondria via active transport and undergo three enzymatic reactions. These reactions ensure that pyruvate can enter the next metabolic pathway so that energy stored in the pyruvate molecules can be harnessed by the cells.
First, the enzyme pyruvate dehydrogenase removes the carboxyl group from pyruvate and releases it as carbon dioxide. The stripped molecule is then oxidized and releases electrons, which are then picked up by NAD+...
First, the enzyme pyruvate dehydrogenase removes the carboxyl group from pyruvate and releases it as carbon dioxide. The stripped molecule is then oxidized and releases electrons, which are then picked up by NAD+...
171.6K
01:17Oxidation of Phenols to Quinones
5.3K
In the presence of oxidizing agents, phenols are oxidized to quinones. Quinones can be easily reduced back to phenols using mild reducing agents. The electron-donating hydroxyl group enhances the reactivity of the aromatic ring, enabling oxidation of the ring even in the absence of an α hydrogen.
o-hydroxy phenols are oxidized to o-quinones and p-hydroxy phenols to p-quinones. Such redox reactions involve the transfer of two electrons and two protons. The reversible redox...
o-hydroxy phenols are oxidized to o-quinones and p-hydroxy phenols to p-quinones. Such redox reactions involve the transfer of two electrons and two protons. The reversible redox...
5.3K