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Transition Metals Transition Metals
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bulk elements trace elements for some species Periodic Table
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General roles of metal ions in biology Na, K: Na, K: Charge carriers Osmotic and electrochemical gradients Nerve function Mg, Ca: Mg, Ca: Enzyme activators Structure promoters Lewis acids Mg 2+ : chlorophyll, photosynthesis Ca 2+ : insoluble phosphates
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Other metal ions: less well defined and more obscure roles Zn: Zn: Metalloenzymes Structure promoters Lewis acid Not a redox catalyst! Fe, Cu, Mo: Fe, Cu, Mo: Electron-transfer Redox proteins and enzymes Oxygen carrying proteins Nitrogen fixation
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Biochemical Reactivity Promotion of Appropriate Geometry Change acid/base character Change Redox potentials Change ionic concentration Formation of Unique species Formation of structural materials Activation of small molecules (NO)
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Fe(II), Fe(III): Essential for ALL organisms In plants: iron deficiency In human body: 4-5 g Uptake: ~ 1 mg/day
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In human body 75% Hem-iron Hemoglobin Myoglobin Cytochromes Oxidases, P-450 25% Non-hem-iron Rubredoxins Ferredoxins
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Porphyrins Fe Fe Oxygen Transport Hemoglobin 4 Fe containing globin units (2-alpha and 2-beta) K increases with each O 2 added Fe(II) does not oxidize to Fe(III) Non-aqueous or simultaneous Oxygen to two hemes. Oxygen Storage Myoglobin 1 heme group
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Porphyrin
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Hemoglobin
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Fe
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Iron Environment in Myoglobin
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Cytochromes, Peroxidases, and Catalases Cytochrome P-450 Cytochrome P-450 Oxidation catalyst Peroxidases/Catalases Peroxidases/Catalases Decomposition of organic peroxides.
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Electron Transfer Chains
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Other Fe Compounds Ferritin / Transferrin Ferritin / Transferrin Iron storage in spleen, liver and marrow. Mw 445,000 (4,300 Fe atoms)
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bulk elements trace elements for some species Periodic Table
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Cu(I), Cu(II) Plants Electron transfer Animals O 2 -carrying Protection of DNA from O 2 - Cu-proteins and enzymes Cytochrome oxidaseO 2 H 2 O Tyrosinase, phenol oxidaseox. of phenols CeruloplasminFe(II) Fe(III) Blue proteinsElectron transfer Superoxide dismutaseElimination of O 2 - HemocyaninO 2 transport
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Superoxide Dismutase SOD-Cu 2+ + O 2.- SOD-Cu 1+ + O 2 SOD-Cu 1+ + O 2.- + 2H + SOD-Cu 2+ + H 2 O 2
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Oxygen hemocyanin mollusks and arthropods
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1. Wilson’s disease: Hereditary disfunction of ceruloplasmin Cu 2+ accumulates in liver, brain: dementia, liver failure Administration: Cu-specific chelate 2. Menke’s „kinky hair” syndrome: Hereditary disfunction of intracellular copper transport Copper deficiency symptoms: disturbances in the mental and physical development Therapy: intravenously administered copper compounds 3. Acute copper deficiency Insufficient oxygen utilization in brain 4. Mutations in the copper dependent superoxide dismutase Copper-related Pathological Disorders
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Ni(II) Ni-containing enzymes of bacteria Urease(Vesicle) CO-dehydrogenase Hydrogenases Membranes
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Mo HPO 4 2- Uptake :MoO42- SO 4 2- Molybdenium enzymes NitrogenaseN 2 NH 3 Aldehyde oxidases-CHO -COOH Nitrate reductaseNO 3 - NO 2 - Sulfide oxidaseSO 3 2- SO 4 2- Xanthin oxidasepurin catabolism Formate dehydrogenaseH-COO - CO 2
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Platinum Complexes in Cancer Therapy
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NH 3 Cl Pt Cis-dichlorodiammineplatinum (II) Blocking cell division NH 3 Cl Pt Trans-dichlorodiammineplatinum (II) inactive Cis-tetrachlorodiammineplatinum (IV) biologically active NH 3 Cl Pt Cl Trans-tetrachlorodiammineplatinum (IV) inactive NH 3 Cl Pt Cl
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N N HN NH 2 N N N Pt NH 3 Cisplatin NH 3 Cl Pt Platinum Complexes in Cancer Therapy
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a b NH 3 Pt NH 3 Protein Platinum Complexes in Cancer Therapy
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Injection Blood Toxic side effectCytostatic effect Plasma proteinsBlood stream KidneyTumor cells Other organs Liver Excretion
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Activity of Pt(NH 3 ) 2 X2 complexes XActivity NO 3 - toxic H2OH2O Cl - antitumor Br - antitumor I-I- inactive SCN - inactive NO 2 - inactive CN - inactive (X = ligand)
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a Pt-chelate complex (considerable antitumor activity)
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