What does it mean if an enzyme is denatured?

Enzymes are proteins that are complicated and specific shapes as determined by the primary sequence of amino acids. This gives rise to

the secondary sequence and subsequently the tertiary structure which is the 3-D structure of the enzyme. A key area of the enzyme is the active site which is where the substrate binds to the enzyme. This active site has a unique 3-D shape specific to the shape of the substrate. The shape of the active site is held together by bonds such as hydrogen bonds and week ionic forces. When an enzyme is denatured by extreme temperatures or pH the bonds within the active site of the enzyme are disrupted and as a result the shape of the active site begins to alter and break down. In increasing temperature, increasing kinetic energy to the bonds leads to the breakdown of the shape of the active site. With pH Hydrogen ion interfere with the charges that are needed to maintain the bonds. As a result the substrate no longer fits into the active site, the reaction cannot be catalysed.