Molecule of the Month

December 2006: Creatine

Creatine was discovered by a French chemist named Michel-Eugène Chevreul, who isolated it from skeletal muscle in 1835. He named it “creatine” after Kreas, the Greek word for flesh.

In 1847 Justus von Liebig, a German chemist, found that physical activity increases the amount of creatine. As a result, many scientists believed that muscles used nitrogen-containing molecules as sources of energy.

We now know that muscle contraction is powered by adenosine triphosphate (ATP). Stored energy is released by the hydrolysis reaction:

ATP + H2O -> ADP + phosphate

Creatine (C) is important because it can be converted to an energy-rich compound called creatine phosphate (CP), which serves as a storehouse of reserve energy. When ATP is abundant, an enzyme called creatine kinase catalyzes the reaction:

C + ATP -> CP + ADP

Later, when muscles are working hard, creatine kinase can recharge spent ADP using the reverse reaction:

CP + ADP -> C + ATP

Creatine has become popular as a muscle enhancer. Athletes take creatine, believing it will maximize their strength and performance. However, many studies show that if creatine is already plentiful within the body, the extra is simply excreted.






Creatine

Creatine Phosphate

Adenosine triphosphate (ATP)

Adenosine diphosphate (ADP)