Adenosine triphosphate (ATP) is the most common coenzyme. Adenosine triphosphate is an essential non-vitamin coenzyme that can be produced from nucleotides such as guanine, adenosine, inosine, or uracil. It is the most widely distributed coenzyme in the human body and is responsible for transporting and supplying phosphate and energy to various locations within the cell. Removing the phosphate molecule releases energy that is needed for several essential chemical reactions and physiological functions including blood clotting, muscle contraction, and metabolism. In the absence of coenzyme ATP, the energy available at the cellular level would not be sufficient to sustain normal life functions.