Weak bonds

What are weak bonds?

• Weak bonds are those forces of attraction that, in biological situations, do not take a large amount of energy to break. For example, hydrogen bonds are broken by energies in the order of 4 - 5 kcal/mol.; van der Waals interactions have energies around Kcal/mol. Compare this to the energy needed to break strong bonds

What are the different kinds of weak bonds?

• In biological terms, ionic bonds, hydrogen bonds and van der Waals interactions are considered weak bonds

What are the biological consequences of weak bonds?

• In biological systems weak bonds are being continually broken and refomed without the aid of enzymes. Compare this to covalent bonds
  
  

• . Weak bonds may be easily broken but they are very important because they help to determine and stabilize the shapes of biological molecules. For example they are important in stabilizing the secondary structure (alpha helix and beta peated sheat) of proteins. Hydrogen bonds keep complementary strands of DNA together. Hydrogen bonds participate in enzymic catalysis.

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• Spring 1996 Information