This occurs in a test tube. ATP transfers this energy to what ever it is reacting with. When the new chemical receives the P it is said to be phosporylated. Phosphorylation has occurred. ATP is renewable.
Enzymes are proteins that act on a substance called a substrate.
In the above reaction the enzyme's active site binds with the substrate. This active site is specific for each different type of substrate. Even the slightest change in the form of this site will alter the enzyme's function. Enzymes work best at temperatures between 35 o and 40 o C in humans. Salts inhibit enzyme action.