text: Enzymes are proteins, and high temperatures cause them to denature (a process that results in the shape of the protein changing).  The shape and structure of an enzyme are vital to its ability to bind with a substrate, so once the enzyme is denatured, it will no longer be able to function.\n\nA prolonged fever could raise body temperatures high enough to denature enzymes.  Since enzymes are important for many body activities (without enzymes many chemical reactions in the body would not occur at all, occur very slowly, or result in different products) such as digestion, denaturation of many of the body's enzymes could be dangerous.  \n\nFor more information on enzymes...\nhttp://en.wikipedia.org/wiki/Enzyme