Depending on where it is normally located in the body, an enzyme will have different temperature and pH values at which its structure is most stable. As conditions deviate from this point, the enzyme’s ability to help along reactions decreases.

 

    Most enzymes work best near a pH of 7, but some enzymes operate most effectively in a particularly acidic environment, such as the stomach; a neutral environment impairs their function. Likewise, the enzymes of creatures that live at high temperatures, such as bacteria that live in hot springs, do not function properly at human body temperature.

 

    Cofactors and Inhibitors

 

    In order to control enzyme activity more precisely, the body has developed a number of compounds that turn enzymes on or off and make them work faster or slower. Sometimes these compounds attach to the active site along with the substrate, and sometimes they bind to another site on the enzyme. Activators of enzymes are known as cofactors or coenzymes. Many vitamins are coenzymes. Molecules that prevent enzymes from functioning properly are known as inhibitors.