Oxygen. Oxygen Terrestrial distribution: 3rd of the most frequently occurring elements: (H, He, O 2 ) 16 8 O (99 %) 18 8 O (izotóp) Bioinorganic importance.

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Presentation transcript:

Oxygen

Oxygen Terrestrial distribution: 3rd of the most frequently occurring elements: (H, He, O 2 ) 16 8 O (99 %) 18 8 O (izotóp) Bioinorganic importance of oxygen: O OO ORGANOGENIC element

O 2 + oxygen ion: no biological importance O oxygen atom: reactive (decomposition O 3 ) O 2 - superoxide anion: UV, enzyme reactions (xanthinoxidase, NADPH-oxidase) (xanthinoxidase, NADPH-oxidase) O 2 2- peroxide anion: dissociation of H 2 O 2 OH hydroxy free radical: decomposition of H 2 O 2 HO 2  hydroperoxy free radical

Activated derivatives Bioinorganic Chemistry

1O2 singlet oxygen  *2p x  *2p y, p z  2p y, p z  2p x Ground state Singlet state

Enzyme reactions Drugs Inflammation Oxygen Free Radicals Pollutants (O 3, NO 2 ) UV Light Radiation Smoking

Oxygen Free Radicals Emphysema Cancer Membrane lipids Nucleic acids Proteins CardiovascularNeurologicalDisorders Aging Cataract

Reactive Oxygen Species Cell adhesion DNA damage Inactivation of NO Inflammation Cancer Membrane damage Oxidation of LDL Atherosclerosis Microcirculation injury Hypertension Cell injury (Cancer therapy)

Reactive oxygen species and free radicals O 2 ·- Superoxide radical H2O2H2O2H2O2H2O2 Hydrogen peroxide HO· Hydroxyl radical 1O21O21O21O2 Singlet oxygen HOO· Hydroperoxyl radical ROOHAlkylhydroperoxide ROO· Alkylperoxyl radical RO · Alkoxyl radical CIO - Hypochlorite ion Fe 4+ O Ferryl ion Fe 5+ O Periferryl ion NO· Nitric oxide

Reduction of O 2 to H 2 O  °(v)

dioxygenase 1.Oxygenases monoxygenase 2.OxydasesO 2 -, H 2 O 2 or 2H 2 O 2.Oxydases O 2 -, H 2 O 2 or 2H 2 O electron acceptor Activator enzymes:

Protection from superoxide and peroxide 1. Superoxide dismutase systems 2. Catalase (heme) 3. Peroxidase systems (heme) A

Superoxide Dismutase SOD-Cu2+ + O2.-  SOD-Cu1+ + O2 SOD-Cu1+ + O H+  SOD-Cu2+ + H2O2

Catalase catalyzes the breakdown of hydrogen peroxide, (H 2 O 2 ) a toxic by product of metabolic reactions, to the harmless substances, water and oxygen. Proteins with catalytic behaviours - Enzymes

Catalase

O 2 + free electron O 2 - superoxide radical H2OH2O H2O2H2O2 H2OH2O GSH GSSG H2OH2OH 2 O + O 2 H 2 O 2 + O 2 - superoxide radical O 2 + OH - + · OH hydroxyl radical H 2 O 2 + Fe 2+ Fe 3+ + OH - + ·OH hydroxyl radical Fenton’s reaction Haber-Weiss’ reaction Pathological state superoxide dismutase catalase glutathion peroxidase Physiological state

MACROPHAG Bakterie O2O2 O 2 (Superoxid) H2O2H2O2 Respiratory burst Myeloperoxidase Superoxid dismutase NADPH Oxidase NADP + Cl - Fe 2+ Fe 3+ OH - HOCl Bak terie Bakt erie Bacterium Phagolysosom Oxygen radical production by phagocytes

Biochemistry Reactive Oxygen Species O2-O2- H2O2H2O2 XO NOX Fenton LOOH Aconitase inhibition COX LipOX MAPK NFkB p53 Antimicrobial Peroxidases NO 2 Cl - HOCl HOBr Br - NO 2 - NOS unc