Loomis & Lipmann
50
NADH
12,4 kcal/mol
-0.2
Eo´ (volts)
FMN
0.0
40
CoQ
b
30
9,2 kcal/mol
+0.2
c1
c
a3
20
+0.4
24,8 kcal/mol
+0.6
+0.8
10
O2
1) Ym = 4 kcal/mol
2) Ym = 12 kcal/mol
0
Go´ (kcal/mol relative to O2)
-0.4
Mitochondrial uncoupling is physiologically
mediated by uncoupling proteins
Mecanismo de Produção de Calor pelo Tecido Adiposo Marrom
Termografia do infravermelho
emitido pela superfície dorsal de
um rato com uma semana de
vida. O ponto amarelo "quente"
se sobrepõe ao depósito de BAT.
Brown adipose tissue is rich in mitochondria
and uncoupling protein 1
Termogênese independente de contração
muscular
BAT (Tecido Adiposo Marrom)
Mamíferos hibernantes
Pequenos mamíferos
Mamíferos jovens (incluindo humanos)
Adapatção ao frio
x132
Tecido Adiposo Branco-WAT
pouco vascularizado
poucas mitocôndrias
x132
Tecido Adiposo Marrom-BAT
altamente vascularizado
muitas mitocôndrias
Responsiveness of BAT related to gender and age
BAT activity contributes to energy expenditure in adult humans
Methamphetamine-induced malignant hyperthermia are mediated by
mitochondrial uncoupling
Pharmacology: uncoupling the agony from ecstasy.
Mills EM, Banks ML, Sprague JE, Finkel T.
Nature. 2003 Nov 27;426(6965):403-4.
Mitochondrial uncoupling reduces insulin secretion
in pancreatic beta cells
Energy from electrons flow generates heat
in plants !!!
Roger Seymour
University of Adelaide
Australia
Heat generation in thermogenic plants depends
on the increase of oxygen consumption
Heat generation in thermogenic plants depends
on the increase of oxygen consumption
A long time ago in a galaxy
Not so far away ...
Mitochondria may allow multicellular organization
through increased the energy efficiency
Carboniferous gigantism is related to increased
atmosferic levels of oxygen
Meganeura sp.
A encruzilhada dos anaeróbicos...
Exposição à O2 100% causa lesão pulmonar
Oxigênio possui elétrons desemparelhados
Free radicals
• Atoms or molecules that have at least one unpaired electron.
• Reach equillibrium donating or removing na electrons from the
nearest molecule.
• Highly reactive species !
Reactive oxygen species
(ROS)
Derived from molecular oxygen
Free radicals
superoxide, O2 · Hydroxyl radical, OH ·
Peroxyl radical, ROO ·
Alkoxyl radical, RO ·
Hydroperoxyl radical, HO2 ·
Non-radical reactive oxygen
species
Hydrogen peroxide, H2O2
(Fenton´s reaction)
Hypochlorous Acid, HClO
Ozone, O3
Free radical theory of aging
AGING - A THEORY BASED ON FREE-RADICAL AND RADIATION-CHEMISTRY
HARMAN, D.
JOURNALS OF GERONTOLOGY, 11, 3, 298-300
Free radical theory of aging
AGING - A THEORY BASED ON FREE-RADICAL AND RADIATION-CHEMISTRY
HARMAN, D.
JOURNALS OF GERONTOLOGY, 11, 3, 298-300
Evidence
1) Longer lived species exhibit decreased levels of oxidative damage, decreased susceptibility to oxidative stress, and
decreased generation of reactive oxygen species.
2) Results have demonstrated that the overexpression of catalase, increased both the average lifespan and maximum
lifespan of mice by 20%.
3) Mutant strains of Caenorhabditis elegans that are more susceptible to free radicals have shortened lifespans, and
vice versa.
4) Drosophila that have mutations in enzymes relating to reactive oxygen species metabolism have also been shown
to have dramatically reduced life-spans, increased susceptibility to oxidative stress and ionizing radiation, partial
female and complete male sterility.
5) Antioxidant supplementation has not been conclusively shown to produce an extension of lifespan in a mammal.
Mitochondria represent one of the major sources of ROS/RNS
A geração
das ROS depende
do estado metabólico
daYm
mitocôndria
Mitochondrial
ROS generation
depends of
ROS
The ‘good side’ of free radicals
a massive production of ROS as immunity instrument
Leukocytes
Macrophages
Lymphocytes
Myeloperoxidase = hypochlorpous acid
NADPH oxidase = superoxide
Bernard Babior
BIOLOGICAL DEFENSE MECHANISMS - PRODUCTION BY LEUKOCYTES OF SUPEROXIDE
A POTENTIAL BACTERICIDAL AGENT.
BABIOR, BM; KIPNES, RS; CURNUTTE, JT. JOURNAL OF CLINICAL INVESTIGATION, 52, 3, 741-744
Oxidative damage to lipids
Damage
• unsaturated bonds loss
• RONS metabolites
generation (aldehydes)
Sequel
• changes in fluidity and
permeability of
membranes (cell lysis)
• membranes integral
enzymes are influenced
Oxidative damage to proteins
Damage
• agregation, fragmentation
and cleveage
• reaction with heme iron
• functional group
modification
Sequel
• changes in enzyme
activity
• Proteolysis
• Aggregation
Oxidative damage to DNA
Damage
• saccharide ring
cleveage
• base modification
• chain breakeage
Sequel
• mutation
• translation mistakes
• Protein synthesis
inhibition
Equilibrium failure between generation and removal
of ROS / RNS leads to
Oxidative stress
Antioxidant defenses
Preventives
Inhibit ROS/RNS generation
Scavengers
Scavenge unpaired ROS/RNS electrons
Repair
Correct molecules damaged by ROS/RNS
Antioxidants and scavengers
• enzymes
Superoxide dismutase, Catalase, Glutathione peroxidase
• nonenzymatic
a) fixed in membranes ( -tocopherol, -carotene)
b) out of membranes (ascorbate, transferrin, bilirubin)
Antioxidant enzymes in mitochondria
H2O + ½ O2
CATALASE
-
SOD
H2O2
[ O2 ]
NADPH.H+
Fe2+
Fenton
reaction
2GSH
GPx
NADP+
GR
GSSG
2 H2O
OH. + Fe3+ + OH-
Low-molecular weigth antioxidants I
Ascorbate (vitamin C)
a)
b)
c)
Important antioxidant in extra and in intracellular compartments
Present in aqueous environments
Reduces O2 · ,- OH ·, ROO·, RO ·
Low-molecular weight antioxidants II
-tocopherol (vitamin E)
a)
b)
Membrane associated antioxidant
Stored mainly in the adipose tissue, the liver and in muscles, the
principal role of vitamin E is as a powerful antioxidant, protecting
body cells from the detrimental effects of free radicals and protecting
unsaturated lipids against oxidation.
Low-molecular weight antioxidants III
Glutathione
a) Tripeptide present in all mammalian cells (SH group)
b) Important redox buffer (2 GSH  GSSG + 2e- + 2H+)
c) ROS elimination, stabilisation in reduction form
(SH-groups, tocopheryl and ascorbate regeneration)
d) Substrate of glutathione peroxidases
Parkinson’s Disease & ROS