RADICALES LIBRES

1. RADICALES LIBRES ESPECIES REACTIVAS DE OXIGENO (ROS) Y DE NITROGENO

3. ROS

4. �D�nde se produce normalmente ROS?

5. ROS production - I Mitochondria ATP generating organellesE.T.C. system common to all life electron leak - birds, bats, other mammalsState 3 and 4 Turtles, ischemia/reperfusion 90% ROS are generated here Membrane potential and ROS production 70% Japanese centanarians have mutation in complex 190% ROS are generated here Membrane potential and ROS production 70% Japanese centanarians have mutation in complex 1

6. ROS production - II

7. Efectos de los ROS sobre las mol�culas biol�gicas

9. Radical Mediated Cleavage of Peptide Bonds Instead of forming carbonyl adduct products, ROS can directly cleave and oxidize the peptide bond. Table 1 illustrates the four most common types of radical mediated cleavages and the corresponding products. Table 1

10. Deamidation, Racemization and Isomerization of Protein Residues Besides introducing carbonyl groups into the protein, ROS are also responsible for deamidation, racemization and isomerization of residues. Gln and Asn residues deamidate and racemize about their C alpha atoms to the D-isomers. Asymmetric side chains of Thr and Ile residues convert from the L-isomer to the D-isomer. Spontaneous prolyl cis-trans isomerization occurs.

11. Modified Proteins Which Are Not Degraded The previous slides dealt with chemical modifications which lead to protein degradation, but not all aberrant proteins are recognized by degradation systems in the cells. For example, modified proteins in eye lens are not recognized. Therefore, modified lens proteins accumulate over a lifetime with deleterious effects to vision. Chemically modified lens proteins lead to the formation of cataracts.

15. Hydroperoxides - Sources

16. Fate of Hydrogen Peroxide

17. Hydroperoxides & Cellular Oxidative Damage

18. Mecanismos anti-oxidantes

20. Reaccion de la Superoxido Dismutasa

24. Cellular Defense Mechanisms to Prevent ROS Buildup. Due to the oxygen rich environment in which proteins exist, reactions with ROS are unavoidable. Superoxide dismutase and glutathione peroxidase are natural antioxidants present in organisms which eliminate some ROS. Glutathione peroxidase catalyzes the reduction of peroxide by oxidizing glutathione (GSH) to GSSG.

25. Trypanothione metabolism in trypanosomatids

26. Defense against ROS

37. Radicales de nitrogeno

41. 1885 1955

43. El estr�s oxidativo y su relaci�n con el envejecimiento

44. La Hip�tesis de la Tasa de Vida �La tasa metab�lica de una especie determina su expectativa de vida�

45. Relaci�n entre metabolismo y envejecimiento En 1957 Denham Harman propone la teor�a de envejecimiento por radicales libres En 1969 se identifica la superoxido dismutasa (SOD) Se unifica empiricamente el concepto de �a mayor tasa metab�lica, mayor producci�n de ROS, menor tiempo de vida� Se corrige y se simplifica la correlaci�n ROS y longevidad

46. Los oxidantes contribuyen al desarrollo del fenotipo de senescencia Fibroblastos crecidos en baja tensi�n de O2 viven mas tiempo Fibroblastos crecidos en baja tensi�n de O2 reducen su tiempo de vida y presentan acortamiento de telomeros mas r�pido H2O2 detienen el crecimiento celular y muestran senescencia Efecto de Ras puede ser revertido por anti oxidantes permeables

47. Mitochondrial respiratory Chain increased oxygen consumption produces more O2.- and H2O2. Xanthine oxidase Insufficient blood flow (hypoxia) leads to degradation of ATP to hypoxanthine producing O2.- and H2O2 . Neutrophil (PMN) Respiratory burst by NADPH oxidase IL-1, IL-6 and TNF-? increases adhesion molecules and PMN infiltration Lipoxygenase/cycloxygenase Activated by cytokines, hormones and toxins

48. Source of Free Radicals in Skeletal Muscle An acute bout of exercise in rats increases ROS production in skeletal muscle. Aged rats generates more ROS at rest and during exercise (15 m/min, 0%) at the same relative workload as young rats (25 m/min, 10%). Both mitochondria and NADPH oxidase are sources of ROS in young muscle during exercise. For aged muscle, mitochondria seem to be the main source. ROS generation is also increased in the heart. With 2 mM pyruvate and 2 mM malate as mitochondrial respiration substrates Replace pyr- malate wiith 1.7 mM ADP, 0.1 mM NADPH and Fe+3 Ji & Bejma J.A.P. (1999)

49. p53 puede presentar un loop de retroalimentacion pro-apoptotica

50. Control + Peroxido de hidr�geno

51. Antioxidant activity vsLipid (LDL) Peroxidation

52. ROS manipulation Dietary supplementation Very mixed results except in particular cases such as Vitamin E and ischemea/reperfusion Dietary Restriction (up to 50% LS extension) Less evidence of oxidative damage Metabolic rate unaltered  Mitochondria characteristics � lipid membrane, less ROS with same membrane potential Exercise (up to 10% LS extension) Acute can lead to immune response and damage Depletion of Vitamin E Training generally beneficial with more mitochondria produced 

53. �Es casi un milagro que los m�todos modernos de ense�anza no hayan estrangulado a�n enteramente la sagrada curiosidad de la investigaci�n; para lo cual �sta peque�a planta, necesita mas que nada, adem�s de estimulaci�n, libertad

54. The problem with vitamin Cantioxidant or pro-oxidant ?

55. 1 All antioxidants may be prooxidants2 Regulated antioxidant system - Redox3 Other natural agents � OVERDOSES?