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Virtual Free Radical School. Iron Chelation in Biology. Alvin L. Crumbliss Department of Chemistry Duke University Box 90346 Durham, NC 27708-0346 Telephone: (919) 660-1540 Fax: (919) 660-1605 E-mail: alvin.crumbliss@duke.edu Website: http://www.chem.duke.edu/%7Ealc/labgroup/.
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Virtual Free Radical School Iron Chelation in Biology Alvin L. Crumbliss Department of Chemistry Duke University Box 90346 Durham, NC 27708-0346 Telephone: (919) 660-1540 Fax: (919) 660-1605 E-mail: alvin.crumbliss@duke.edu Website: http://www.chem.duke.edu/%7Ealc/labgroup/ Iron in Biology Society For Free Radical Biology and Medicine Crumbliss1
Iron Chelation in Biology Tutorial Guide Introduction: Biological Iron Coordination Chemistry Panels 3, 4 & 5 Chelation and Solubility Panel 6 Chelation and Redox Potential Panel 7 Common Iron Ligands in Biology Panel 8 Chelate Stability Definitions Panel 9 Chelation and Redox Control Panels 10, 11 & 12 Oxidation State Influence on Chelate Stability Panel 13 Iron Chelation and Transport Panels 14, 15 &16 Influence of pH on Chelate Stability Panel 17 Influence of Chelate Stability on E0 Panel 18 Influence of Chelation on Kinetics Panel 19 Iron in Biology Society For Free Radical Biology and Medicine Crumbliss2
Introduction: Biological Iron Coordination Chemistry 1st coordination shell; immediate chemical environment Common oxidation states: +2, +3 Common coordination numbers: 4, 5, 6 3 Iron in Biology Society For Free Radical Biology and Medicine Crumbliss3 References [1,2]
Introduction: Biological Iron Coordination Chemistry 4 Iron in Biology Society For Free Radical Biology and Medicine Crumbliss4 References [1,2]
Introduction: Biological Iron Coordination Chemistry The first coordination shell Prevents hydrolysis/precipitation Influences molecular recognition Controls redox potential Controls mobility 5 Iron in Biology Society For Free Radical Biology and Medicine Crumbliss5
Iron Chelation and Solubility • Fe insoluble due to hydrolysis • Strong chelators prevent hydrolysis and precipitation 6 Iron in Biology Society For Free Radical Biology and Medicine Crumbliss6
Iron Chelation and Redox Potential Fe(III/II) redox potential varies significantly with ligands in 1st coordination shell e.g. Desferal 7 Iron in Biology Society For Free Radical Biology and Medicine Crumbliss7
Common Iron Ligands in Biology (VI) (II) (V) (IV) (III) (I) (VIII) (VII) (IX) Iron in Biology Society For Free Radical Biology and Medicine Crumbliss8 8
Iron Chelate Stability Definitions 9 Iron in Biology Society For Free Radical Biology and Medicine Crumbliss9 References [3,4,5,6]
Iron Chelation and RedoxControl Why is it important? Iron in Biology Society For Free Radical Biology and Medicine Crumbliss10 10 Reference [6]
Iron Chelation and RedoxControl Why is it important? 11 Iron in Biology Society For Free Radical Biology and Medicine Crumbliss11 Reference [6]
Iron Chelation and RedoxControl Why control E0? 12 Iron in Biology Society For Free Radical Biology and Medicine Crumbliss12 Reference [6]
Oxidation State Influence on Chelate Stability t = 4 ms 1/2 3+ 3+ Fe(OH ) + * OH Fe(OH ) ( * OH ) + OH 2 6 2 2 5 2 2 - - e + e - t = 0.2 s 1/2 2+ 2+ Fe(OH ) + * OH Fe(OH ) ( * OH ) + OH 2 6 2 2 5 2 2 Thermodynamics Kinetics 13 Iron in Biology Society For Free Radical Biology and Medicine Crumbliss13 References [7,8,9,10,11]
Iron Chelation and Transport 14 Iron in Biology Society For Free Radical Biology and Medicine Crumbliss14 Reference [7]
Iron Chelation and Transport Iron in Biology Society For Free Radical Biology and Medicine Crumbliss15 15 References [4,5,6]
Iron Chelation and Transport desferrioxamine B Fe(III)-enterobactin complex 110 = 1049 ; pFe = 35.5 enterobactin ferrioxamine B complex 110 = 1030.2 ; pFe = 26.6 Iron in Biology Society For Free Radical Biology and Medicine Crumbliss16 16 References [4,5,6]
Influence of pH on Fe(III)-Chelate Stability (I) (II) 17 Iron in Biology Society For Free Radical Biology and Medicine Crumbliss17 Reference [9,12]
Influence of Fe(III)-Chelate Stability on E0 18 Iron in Biology Society For Free Radical Biology and Medicine Crumbliss18 References [6,10,13,14]
Influence of Fe(III)-Chelation on Kinetics k1= 1.8 M-1s-1 k2 = 8.1 x 102 M-1s-1 19 Iron in Biology Society For Free Radical Biology and Medicine Crumbliss19 Reference [5,15]
References 20 Iron in Biology Society For Free Radical Biology and Medicine Crumbliss20
References Acknowledgements 21 Iron in Biology Society For Free Radical Biology and Medicine Crumbliss21