C9. Metal ions in biological systems

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C9. Metal ions in biological systems

• April 4th

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General

• Many metal ions have role in biological processes
  of the body
• The ions have different physical and chemical
  properties
• Charge density
• Complex formation
• Oxidation states
• Minerals in food

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The most important ions

• Ion
• Ca2
• Mg2
• Fe2
• Cu2
• Zn2
• Co3
• Na
• K

• Role
• 1.5-2 of body mass, bones, teeth
• Bones and teeth, intracellular activity
• Hemoglobin, O2 transfer
• Cofactor in enzymes
• Cofactor in enzymes,growth, healing
• In vitamin B12
• Water balance, nerve impulses, fluids inside and
  outside cells

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ATP adenosine triphosphate

• A nucleotide (ribose sugar, adenine base and
  three phosphate groups)
• Energy currency of the cell, providing the energy
  for most of the energy-consuming activities
• It regulates many biochemical pathways

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ATP as energy source

• The exothermic reaction is (hydrolysis)
• ATP H2O ? ADP Pi E
• ADP is adenosine diphosphate
• Pi is phosphate group, HOPO32-
• Reversible process

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Na/K pump

• Found in membranes of cells.
• Produces electrical and chemical gradient across
  a cell membrane.
• It plays a very important role in nerve cell
  membranes.
• Transmission of nerve impulses.
• Channel tunnel-like trans membrane protein
  Na-K ATPase
• K inside a cell
• Na outside a cell
• Cell surface membranes pump Na ions out of cell
  and K in.

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Na/K pump

• The pump requires energy
• ATP H2O ? ADP Pi E
• With 1 mol ATP
• 3 mol of Na and 2 mol of K pumped out/in
• Animation

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Electron transport

• Energy from food is released through many redox
  reactions (mitochondria)
• Transition metals have many oxidation states.
• gt They can carry charges.
• Cytochromes are oxidizing enzymes.
• Contain copper or iron as cofactors.
• Cu2 e ? Cu Fe3 e ? Fe2
• Animation

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Cu in cytochrome oxidase
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Hemoglobin as oxygen carrier

• In each hemoglobin molecule there are four heme
  groups
• Heme Fe2 surrounded by phorphyrin group, four
  N act as ligands.
• As O2 carrier O2 binds to Fe2 as a ligand
• Reversible process
• CO and CN bind irreversible to Fe2

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Hemoglobin
Binding of O2 alters the structure