Roles of Metal Ions in Biochemistry

Two-thirds of all the elements are metals. One of their most important properties is that they cannot readily be ionized. This means they survive in the body in their ionic form, and can take part in many biological reactions. Because there are so many roles of metal ions in biochemistry, they must be divided into categories and explained using examples.

RNA Molecules and Protein Synthesis

• Although low ionization is usually beneficial for metal ions in biochemistry, the more reactive metals may have furthered the evolution of ribonucleic acid (RNA) molecules into modern protein synthesis machines. Protein synthesis is the mechanism that allows humans to build complex molecules such as enzymes, chaperones and cellular transportation proteins. Magnesium and Potassium are two examples of useful metal ions in RNA biology. They are both cationic species which can bond closely to polyanionic RNA and can assist the RNA molecule during folding, which means it works more effectively during protein synthesis.

Enzyme Catalysis

• Metal ions play an important role in metal complex formation and work closely with many enzymes in the body. They are the mediators or "co-substrates" of many enzyme-related reactions, bonding briefly to a section of the molecule, bringing it together with its substrate, then releasing it again when the correct reaction has taken place. DNA Ligase is an example of an enzyme that has a metal ion present in its active site during the reaction phase, or "catalysis." The metal ion helps speed up the reaction by drawing the substrate into the active site and holding it there using electrostatic forces. Metallo-enzymes are formed when the metal ion binds more strongly to the enzyme, creating a stable complex, like the iron in hemoglobin in blood.

Energy Use in Muscles

• Magnesium works with the ATP (adenosine triphosphate) complex to allow your muscles to derive energy from food. This is another essential life process. Metal ion catalysis causes a stabilization of developing negative charge on the parts of the substrates that are trying to exit the active site of the ATP complex. This frees them up to leave, so correct processing can continue. If the substrate did not exit the molecule after the reaction phase, the ATP would be unable to accept new substrates. No new energy would be taken for muscle function.

Gene Regulation and Disease Control

• Approximately one-third of all known proteins contain metal ions as cofactors. One important function these metal chelates, or complexes, perform is in the regulation of genes, which is vital for survival of the species. Many diseases, including genetic defects, have been identified as being solely caused by defects, inconsistencies and incorrect metabolism of metal ions in the body. Platinum metals, which have rich stereochemistry and can act as strong, effective co-factors, are not known for their occurrence in the body. They are now being used in research to develop faster, more efficient reaction biochemistries, which may be able to help prevent or treat diseases like hemochromatosis and Menkes Disorder.

Iron Storage

• Iron is essential to your body for many reasons, not least its important function in the blood and liver. Iron cannot be absorbed or removed from the body without the assistance of complex molecules called "chelators." Transferrin is a naturally occurring example. Iron chelators help absorb iron from the gastrointestinal tract, but some people have a condition which means they absorb too much. If the excess iron is not removed and excreted, they can develop a potentially life-threatening case of iron toxicity. This represents an interesting balance between the correct function of a metal ion complex and a deadly loss of function. Synthetic chelates are being designed to treat iron overload.