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Clase lipogénesis
- 1. M. en C. Rodrigo Martínez Espinosa Bioquímica, Medicina. 2.3 Lipogénesis 2.Metabolismo de los lípidos
- 2. Acetil-CoA
- 3. Acetil-CoA carboxilasa Forma la Malonil-CoA 1)Proteína acarreadora de biotina. 2)Biotin carboxilasa. 3)Transcarboxilasa.
- 7. Sintasa de ácidos grasos (FAS): Adiciona 2 carbones en 4 reacciones
- 8. Ejemplo: síntesis de Palmitato.
- 9. Proteína acarreadora de acil. Mantiene el sistema unido.
- 20. Lanzadera de grupos acetilo de la mitocondria al citosol.
- 21. Regulación de síntesis de ácidos grasos .
- 22. Rutas de formación de otros ácidos grasos.
- 23. Desaturación.
- 24. Prostaglandinas y tromboxanos Intermediarios en inflamación, dolor y fiebre.
- 25. Triacilgliceroles Biosíntesis de ácido fosfatídico (precursor de trigliceridos). Glicerol Glicerol + 2 ác. grasos
- 26. Glicerol + 3 ác. grasos
- 29. “ Ciclo” de triacilglicerol
- 33. Síntesis de fosfolípidos Formación de membranas celulares
- 35. CONCLUSIONES Los ác. grasos son sintetizados a partir de acetil-CoA vía seis reacciones enzimáticas en el citosol. Malonil-CoA es la primer molécula formada y es el principal regulador de la síntesis de ác. grasos. Las hormonas insulina, glucagón y epinefrina son importantes reguladores en la síntesis de ác. Grasos. Los trigliceridos están formados por una molécula de glicerol y tres moléculas de ác. Grasos. Los trigliceridos son la principal reserva energética del cuerpo. Las prostanglanidas y los tromboxanos son sintetizados a partir de ác. Grasos, por la enzima COX.
- 36. M. en C. Rodrigo Martínez Espinosa Bioquímica, Medicina. 2.4 Metabolismo del colesterol 2.Metabolismo de los lípidos
- 38. El Colesterol es sintetizado en 4 estados a partir de Acetil-CoA.
- 39. Estado 1 Acetil-coA a Mevalonato
- 40. Estado 2 Mevalonato a Isopreno activado
- 41. Estado 3 Isopreno activado a Escualeno
- 42. Estado 4 Escualeno a Colesterol
- 48. Regulación de la síntesis del colesterol
- 49. Hormonas Esteroideas derivadas de colesterol.
Notas del editor
- FIGURE 21-1 The acetyl-CoA carboxylase reaction. Acetyl-CoA carboxylase has three functional regions: biotin carrier protein (gray); biotin carboxylase, which activates CO 2 by attaching it to a nitrogen in the biotin ring in an ATP-dependent reaction (see Figure 16-16); and transcarboxylase, which transfers activated CO 2 (shaded green) from biotin to acetyl-CoA, producing malonyl-CoA. The long, flexible biotin arm carries the activated CO 2 from the biotin carboxylase region to the transcarboxylase active site. The active enzyme in each step is shaded blue.
- FIGURE 21-1 (part 1) The acetyl-CoA carboxylase reaction. Acetyl-CoA carboxylase has three functional regions: biotin carrier protein (gray); biotin carboxylase, which activates CO 2 by attaching it to a nitrogen in the biotin ring in an ATP-dependent reaction (see Figure 16-16); and transcarboxylase, which transfers activated CO 2 (shaded green) from biotin to acetyl-CoA, producing malonyl-CoA. The long, flexible biotin arm carries the activated CO 2 from the biotin carboxylase region to the transcarboxylase active site. The active enzyme in each step is shaded blue.
- FIGURE 21-1 (part 2) The acetyl-CoA carboxylase reaction. Acetyl-CoA carboxylase has three functional regions: biotin carrier protein (gray); biotin carboxylase, which activates CO 2 by attaching it to a nitrogen in the biotin ring in an ATP-dependent reaction (see Figure 16-16); and transcarboxylase, which transfers activated CO 2 (shaded green) from biotin to acetyl-CoA, producing malonyl-CoA. The long, flexible biotin arm carries the activated CO 2 from the biotin carboxylase region to the transcarboxylase active site. The active enzyme in each step is shaded blue.
- FIGURE 21-1 (part 3) The acetyl-CoA carboxylase reaction. Acetyl-CoA carboxylase has three functional regions: biotin carrier protein (gray); biotin carboxylase, which activates CO 2 by attaching it to a nitrogen in the biotin ring in an ATP-dependent reaction (see Figure 16-16); and transcarboxylase, which transfers activated CO 2 (shaded green) from biotin to acetyl-CoA, producing malonyl-CoA. The long, flexible biotin arm carries the activated CO 2 from the biotin carboxylase region to the transcarboxylase active site. The active enzyme in each step is shaded blue.
- FIGURE 21-6 Sequence of events during synthesis of a fatty acid. The mammalian FAS I complex is shown schematically, with catalytic domains colored as in Figure 21-3. Each domain of the larger polypeptide represents one of the six enzymatic activities of the complex, arranged in a large, tight "S" shape. The acyl carrier protein (ACP) is not resolved in the crystal structure shown in Figure 21-3, but is attached to the KS domain. The phosphopantetheine arm of ACP ends in an — S H. After the first panel, the enzyme shown in color is the one that will act in the next step. As in Figure 21-4, the initial acetyl group is shaded yellow, C-1 and C-2 of malonate are shaded pink, and the carbon released as CO 2 is shaded green. Steps 1 to 4 are described in the text.
- FIGURE 21-6 (part 2) Sequence of events during synthesis of a fatty acid. The mammalian FAS I complex is shown schematically, with catalytic domains colored as in Figure 21-3. Each domain of the larger polypeptide represents one of the six enzymatic activities of the complex, arranged in a large, tight "S" shape. The acyl carrier protein (ACP) is not resolved in the crystal structure shown in Figure 21-3, but is attached to the KS domain. The phosphopantetheine arm of ACP ends in an — S H. After the first panel, the enzyme shown in color is the one that will act in the next step. As in Figure 21-4, the initial acetyl group is shaded yellow, C-1 and C-2 of malonate are shaded pink, and the carbon released as CO 2 is shaded green. Steps 1 to 4 are described in the text.
- FIGURE 21-6 (part 3) Sequence of events during synthesis of a fatty acid. The mammalian FAS I complex is shown schematically, with catalytic domains colored as in Figure 21-3. Each domain of the larger polypeptide represents one of the six enzymatic activities of the complex, arranged in a large, tight "S" shape. The acyl carrier protein (ACP) is not resolved in the crystal structure shown in Figure 21-3, but is attached to the KS domain. The phosphopantetheine arm of ACP ends in an — S H. After the first panel, the enzyme shown in color is the one that will act in the next step. As in Figure 21-4, the initial acetyl group is shaded yellow, C-1 and C-2 of malonate are shaded pink, and the carbon released as CO 2 is shaded green. Steps 1 to 4 are described in the text.
- FIGURE 21-6 (part 4) Sequence of events during synthesis of a fatty acid. The mammalian FAS I complex is shown schematically, with catalytic domains colored as in Figure 21-3. Each domain of the larger polypeptide represents one of the six enzymatic activities of the complex, arranged in a large, tight "S" shape. The acyl carrier protein (ACP) is not resolved in the crystal structure shown in Figure 21-3, but is attached to the KS domain. The phosphopantetheine arm of ACP ends in an — S H. After the first panel, the enzyme shown in color is the one that will act in the next step. As in Figure 21-4, the initial acetyl group is shaded yellow, C-1 and C-2 of malonate are shaded pink, and the carbon released as CO 2 is shaded green. Steps 1 to 4 are described in the text.
- FIGURE 21-6 (part 5) Sequence of events during synthesis of a fatty acid. The mammalian FAS I complex is shown schematically, with catalytic domains colored as in Figure 21-3. Each domain of the larger polypeptide represents one of the six enzymatic activities of the complex, arranged in a large, tight "S" shape. The acyl carrier protein (ACP) is not resolved in the crystal structure shown in Figure 21-3, but is attached to the KS domain. The phosphopantetheine arm of ACP ends in an — S H. After the first panel, the enzyme shown in color is the one that will act in the next step. As in Figure 21-4, the initial acetyl group is shaded yellow, C-1 and C-2 of malonate are shaded pink, and the carbon released as CO 2 is shaded green. Steps 1 to 4 are described in the text.
- FIGURE 21-6 (part 6) Sequence of events during synthesis of a fatty acid. The mammalian FAS I complex is shown schematically, with catalytic domains colored as in Figure 21-3. Each domain of the larger polypeptide represents one of the six enzymatic activities of the complex, arranged in a large, tight "S" shape. The acyl carrier protein (ACP) is not resolved in the crystal structure shown in Figure 21-3, but is attached to the KS domain. The phosphopantetheine arm of ACP ends in an — S H. After the first panel, the enzyme shown in color is the one that will act in the next step. As in Figure 21-4, the initial acetyl group is shaded yellow, C-1 and C-2 of malonate are shaded pink, and the carbon released as CO 2 is shaded green. Steps 1 to 4 are described in the text.
- FIGURE 21-6 (part 7) Sequence of events during synthesis of a fatty acid. The mammalian FAS I complex is shown schematically, with catalytic domains colored as in Figure 21-3. Each domain of the larger polypeptide represents one of the six enzymatic activities of the complex, arranged in a large, tight "S" shape. The acyl carrier protein (ACP) is not resolved in the crystal structure shown in Figure 21-3, but is attached to the KS domain. The phosphopantetheine arm of ACP ends in an — S H. After the first panel, the enzyme shown in color is the one that will act in the next step. As in Figure 21-4, the initial acetyl group is shaded yellow, C-1 and C-2 of malonate are shaded pink, and the carbon released as CO 2 is shaded green. Steps 1 to 4 are described in the text.
- FIGURE 21-6 (part 8) Sequence of events during synthesis of a fatty acid. The mammalian FAS I complex is shown schematically, with catalytic domains colored as in Figure 21-3. Each domain of the larger polypeptide represents one of the six enzymatic activities of the complex, arranged in a large, tight "S" shape. The acyl carrier protein (ACP) is not resolved in the crystal structure shown in Figure 21-3, but is attached to the KS domain. The phosphopantetheine arm of ACP ends in an — S H. After the first panel, the enzyme shown in color is the one that will act in the next step. As in Figure 21-4, the initial acetyl group is shaded yellow, C-1 and C-2 of malonate are shaded pink, and the carbon released as CO 2 is shaded green. Steps 1 to 4 are described in the text.
- FIGURE 21-7 Beginning of the second round of the fatty acid synthesis cycle. The butyryl group is on the Cys — S H group. The incoming malonyl group is first attached to the phosphopantetheine ﾑ S H group. Then, in the condensation step, the entire butyryl group on the Cys — S H is exchanged for the carboxyl group of the malonyl residue, which is lost as CO 2 (green). This step is analogous to step 1 in Figure 21-6. The product, a six-carbon β -ketoacyl group, now contains four carbons derived from malonyl-CoA and two derived from the acetyl-CoA that started the reaction. The β -ketoacyl group then undergoes steps 2 through 4, as in Figure 21-6.
- FIGURE 21-10 Shuttle for transfer of acetyl groups from mitochondria to the cytosol. The mitochondrial outer membrane is freely permeable to all these compounds. Pyruvate derived from amino acid catabolism in the mitochondrial matrix, or from glucose by glycolysis in the cytosol, is converted to acetyl-CoA in the matrix. Acetyl groups pass out of the mitochondrion as citrate; in the cytosol they are delivered as acetyl-CoA for fatty acid synthesis. Oxaloacetate is reduced to malate, which can return to the mitochondrial matrix and is converted to oxaloacetate. The major fate for cytosolic malate is oxidation by malic enzyme to generate cytosolic NADPH; the pyruvate produced returns to the mitochondrial matrix.
- FIGURE 21-11 Regulation of fatty acid synthesis. (a) In the cells of vertebrates, both allosteric regulation and hormone-dependent covalent modification influence the flow of precursors into malonyl-CoA. In plants, acetyl-CoA carboxylase is activated by the changes in [Mg 2+ ] and pH that accompany illumination (not shown here). (b) Filaments of acetyl-CoA carboxylase (the active, dephosphorylated form) as seen with the electron microscope.
- FIGURE 21-22a Regulation of glyceroneogenesis. (a) Glucocorticoid hormones stimulate glyceroneogenesis and gluconeogenesis in the liver, while suppressing glyceroneogenesis in the adipose tissue (by reciprocal regulation of the gene expressing PEP carboxykinase (PEPCK) in the two tissues); this increases the flux through the triacylglycerol cycle. The glycerol freed by the breakdown of triacylglycerol in adipose tissue is released to the blood and transported to the liver, where it is primarily converted to glucose, although some is converted to glycerol 3-phosphate by glycerol kinase.
- FIGURE 21-22 Regulation of glyceroneogenesis. (b) A class of drugs called thiazolidinediones are now used to treat type 2 diabetes. In this disease, high levels of free fatty acids in the blood interfere with glucose utilization in muscle and promote insulin resistance. Thiazolidinediones activate a nuclear receptor called peroxisome proliferator-activated receptor γ (PPAR γ ), which induces the activity of PEP carboxykinase. Therapeutically, thiazolidinediones increase the rate of glyceroneogenesis, thus increasing the resynthesis of triacylglycerol in adipose tissue and reducing the amount of free fatty acid in the blood.