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Porphyrins & Related complexes

Porphyrins & Related complexes. 200901106 김현지. How do inorganic compounds and ions help cause biochemical reaction?. Promotion of reactions by providing appropriate geometry for breaking of forming bonds tetrahedral, octahedral, square-planar Changes in acid-base activity

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Porphyrins & Related complexes

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  1. Porphyrins& Related complexes 200901106 김현지

  2. How do inorganic compounds and ionshelp cause biochemical reaction? • Promotion of reactions by providing appropriate geometry for breaking of forming bonds tetrahedral, octahedral, square-planar • Changes in acid-base activity water bound to metal ion – more acidic than free water • Changes in redox potentials coordination by different ligands changes redox potentials 4. Some ions(Na+,K+,Ca2+,Cl-) act as specific charge carriers, with concentration gradients maintained and modified by membrane ion pumps and trigger mechanisms

  3. How do inorganic compounds and ionshelp cause biochemical reaction? • Organometallic reactions can create species that are otherwise not attainable. • Inorganic ions, both cationic and anionic, are sued as structural units to form bone and other hard structures 7. A few small molecules have specific effects that do not fit easily in to any of the categories above

  4. Porphine , C20H14N4 • The unsubstituted porphyrin • Aromaticity • 1. Heterocyclic • 2. Planar geometry • all the atoms lie in a single plane • 3. Completely conjugated • Sp2 hybridized carbon atoms • 4. 4n+2 pi electrons

  5. Porphyrins Metal ion : surrounded by the four nitrogens of a porphine ring in a square-planar • Axial sites : • available for other ligands Different 1. side chains 2. Metal ions 3. Surrounding species result in very different reactions and roles for these compounds

  6. Porphyrins ① O2 storage and transport : myoglobinand hemoglobin ② electron transport : cytochromesb and c ③ O2 activation and utilization : cytochromeP450 and cytochromeoxidase

  7. Porphyrins Porphyrins can be substituted 12 Position 8 Position : β position pyrrolic ring 4 Position : meso position methine bridge Symmetry : D2h

  8. Green : Elements known to form complexes with porphyrinsRed : Metals found in Nature

  9. Porpyrin related compounds

  10. Iron Porphyrins Hemoglobin and Myoglobin : oxygen transfer and storage agents in the blood and muscle tissue. Myoglobin Hemoglobin

  11. Iron Porphyrins HemoglobinVSMyoglobin Tetramer (= 4 Heme protein) Monomer (= 1 Heme protein)

  12. Iron Porphyrins 1. Hemoglobin • 4Irons can each carry 1O2 One iron binds an oxygen molecule, • the molecular shape changes to make binding of additional oxygen molecules easier - K4 many time larger than the K1

  13. Iron Porphyrins 1. Hemoglobin initial removal of oxygen, the entire load of oxygen is delivered at the required site. • favored by pH changes - Bohr effect • ① The concentration CO2 increases, • ② Formation of bicarbonate • ③ pH to decrease • ④ Increased acidity ⑤ Favors release of O2 from the oxyhemoglobin

  14. Iron Porphyrins 2. Myoglobin similar to a single subunit of hemoglobin

  15. Iron Porphyrins HemoglobinVSMyoglobin Myoglobin & Hemoglobin Binding Curves Myglobin binds O2 more strongly than the first O2 of Hemoglobin But fourth equilibrium constant of hemoglobin is larger than that for myoglobin by a factor of about 50

  16. Iron Porphyrins 1-1. Carboxyhemoglobin Hemoglobin Fe(II) : 70pm out of the plane, typical high-spin d6 ion • CarboxyHemoglobin Fe(II) • : oxygen or carbon monoxide • bond to the sixth position, • - the iron becomes coplanar • with the porphyrin, • - the resulting compound is • diamagnetic CO : strong enough ligand to force spin pairing resulting pi back-bonding stabilizes the complex.

  17. Iron Porphyrins 1-2. Oxyhemoglobin Bonding as nearly that of Fe(III)-O2 Metal-to-ligand electron transfer to result in a simple double bond between the oxygens.

  18. Iron Porphyrins 1-2. Oxyhemoglobin Molecular Orbital Oxyhemoglobin Strong σ interaction : dz2 & πgz Weak πinteraction • : dxz & πgx • Increased ligand field results • In pairing of the electrons & Weakened O-O bond

  19. Iron Porphyrins • Cytochromes & Peroxidases & Catalases Cytochrome P450 catalyzes : oxidation reactions in the liver - adrenal cortex, Helping to detoxify some substances by adding hydroxyl groups - Make the compounds more water soluble & more susceptible to further reactions Peroxidases & Catalases : Fe(III)-hemecompunds that decompose hydrogen peroxide and organic peroxides

  20. Iron Porphyrins Hydrogen peroxide made from Fe(III) &triethylenetetramine(trien) Mechanism of the [Fe(trien)]3+ - H2O2 Tracer studies using 18O-labeled water : oxygengas from peroxide Result : O2 must involve removal of hydrogen from H2O2

  21. Similar Ring Compounds 1. Chlorophylls • Chlorin:Porphine ring + one double bond reduced • ex )chlorophylls • Chlorophylls : green pigments found in plants, • containMagnesium • and start the process of photosynthesis • 2 H2O O2 + 4H+ + 4e- • CO2 + 4H+ + 4e- [CH2O] + H2O • [CH2O] ; sugars, carbohydrates, cellulose

  22. Similar Ring Compounds Other compounds containing metal ions • ion-sulfur proteins with active sites • Involving iron, sulfur, and sulfur-containing amino acids • Fe(II) & Fe(III) in tetrahedralsitesbridged by sulfide ions • Bound into the protein by Fe-S bonds to the amino acid. • Ferredoxins

  23. Similar Ring Compounds Other compounds containing metal ions • Ferredoxins • Clostridialferredoxin: • two identical Fe-S complexes • Cubane structure : • 4S, 4Fe in a distorted cube

  24. Similar Ring Compounds 2. Coenzyme B12 (= Vitamin B12 , cyanocobalamin) Cobaltinto a corrin ring structure One less =CH- bridge between the pyrrole rings than the porphyrins Co(III) , 4 corrinnitrogens • : contribute electrons , charge 2- the benzimidazole nitrogen : contributes 2e- cyanide or adenosine in the sixth position ; contributes 2e- , charge 1- without sixth ligand : cobalamin

  25. Similar Ring Compounds 2. Coenzyme B12 (= Vitamin B12 , cyanocobalamin) ex) Alkylcobalamins depend on cleavage of the alkyl-cobalt bond • Co(I) & alkyl cation • Co(II) & alkyl radical • Co(III) & alkyl anion • With the radical mechanism – most common

  26. Similar Ring Compounds 2. Coenzyme B12 (= Vitamin B12 , cyanocabalamin) alkyl products reaction

  27. Refrence http://en.wikipedia.org/wiki/Porphine http://en.wikipedia.org/wiki/Carboxyhemoglobin http://en.wikipedia.org/wiki/Myoglobin http://en.wikipedia.org/wiki/Cytochrome http://www.thieme-chemistry.com/fileadmin/Thieme/HW-100/pdf/june/9DF.pdf http://www.org-chem.org/yuuki/porphyrin/porphyrin.html http://www.f.u-tokyo.ac.jp/~kanai/seminar/pdf/Lit_K_Yamamoto_M1.pdf http://llg.chem.uni.wroc.pl/?Molecules:Porphyrin_Primer:Properties Molecular symmetry, David J. Wilock, Wiley p17~18 Biochemistry, Stryer 7ed, P752~755 Inorganic chemistry, Gary L miessler, pearson, p 631~640

  28. Question

  29. 감사합니다

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