Creatine: Chemical | Organic composition
Last modified: Thursday, 26. March 2009 - 4:52 am
Endogenous creatine is creatine that is synthesized, or manufactured, within the body by the liver, kidneys, and pancreas. It is produced from the amino acids arginine and glycine, and methionine, and is then transported throughout the body where it is stored in the organs, tissues, and muscles. The body can biosynthesize, or manufacture, up to 2 g of creatine daily. However, animal studies have shown that when supplemental creatine is taken regularly, the amount of endogenous creatine produced by the body is reduced. This tendency is thought to reverse itself once creatine supplementation stops.
The majority of creatine in the body (over 95%) is stored in skeletal muscle. About two-thirds of this is bound with phosphates, forming the compound creatine phosphate (PCr).
PCr acts on anaerobic adenosine triphosphate (ATP), the substance that powers muscle contractions. When ATP powers a muscle contraction, it loses one of its three phosphate molecules, changing from a triphosphate to a diphospate. The phosphate loss converts ATP to ADP (or adenosine diphosphate). Creatine phosphate provides an extra phosphate molecule for the ADP to convert or regenerate quickly back to ATP again and refuel muscle performance. Storing extra creatine in the skeletal muscles theoretically will provide for faster, more frequent ATP conversion.
Creatine monohydrate, the most popular form of off-the-shelf creatine supplementation, is an odorless, white, water-soluble powder. Its chemical name is N-(aminoiminomethyl)-N-methylglycine monohydrate.
In addition to unadulterated creatine monohydrate, special formulations of the supplement are available in the U.S. market which may include supplemental phosphates, amino acids, carbohydrates, and other dietary additives. There have also been laboratory reports of creatine that has been altered during the manufacturing process with other unlabeled and potentially harmful substances.