1. C9. Metal ions in biological systems
April 4th

2. 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

3. The most important ions
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

4. 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

5. 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

7. 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.

8. 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

9. Electron transport
Energy from food is released through many redox reactions (mitochondria)
Transition metals have many oxidation states.
=> They can carry charges.
Cytochromes are oxidizing enzymes.
Contain copper or iron as cofactors.
Cu2+ + e– ↔ Cu+; Fe3+ + e– ↔ Fe2+
Animation

10. Cu in cytochrome oxidase

11. 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+

12. Hemoglobin
Binding of O2 alters the structure