How does a change in PH denature an enzyme?

How does a change in PH denature an enzyme? I'm confused as to HOW it actually works, as in is it to do with bonds or hydrogen ions or what..not too complicated please, not too simplified either.How does a change in PH denature an enzyme?
Proteins are made up of amino acids. Here is the basic structure of an amino acid. http://en.wikipedia.org/wiki/File:AminoA



Under normal pH COOH group is deprotonated (it acts as an acid) and it forms H+ ions in solution. The NH2 group is normally protonated (it acts as a base) to become NH3+.

In addition to this, many amino acid side chains have different forms depending on the pH of the solution and all amino acids have . The structure of proteins depends on hydrogen bonding and dipole-dipole interactions between amino acids. When the pH is changed, the amino acids may not be able to form hydrogen bonds or dipole-dipole interactions anymore and the structure is adversely affected i.e. the protein has become denatured. This is especially true if the pH change affects the amino acids in the active site of the protein.