Creatine: Guest Post from Beauty by the Geeks

Hi there science fans! We here at Antisense Science have teamed up with our good friends over at Beauty by the Geeks to bring you a guest feature on creatine -we love a bit of science cross-pollination! The post was originally part of BBTG’s Molecular Mondays, so check them out after you’ve read this!

Creatine. A molecular gem that you’ve probably heard of in the context of exercise and working out in the gym.  Creatine is used as a supplement by gym-goers and sporty folk when they want to get more out of their workout. It comes from both endogenous and exogenous sources, being produced in the liver and coming from dietary meat and fish.

It’s a compound which can give a runner that extra bit of explosive energy or a weight-lifter a little more strength. This nitrogenous organic acid is composed of three different amino acids and it acts to increase the levels of adenosine triphosphate (ATP) in the muscles in times when an extra energy supply is needed, above and beyond the level of ATP normally found in the body.

In order for us to use ATP as a source of energy, it needs those three phosphate groups stuck onto it. As we use more energy, however, ATP loses a few of these groups in its conversion to ADP (in this case, the D stands for “di”).

Molecular Structure of Creatine

In the body, most creatine is found as phosphocreatine – creatine with an extra phosphate group on. Phosphocreatine donates a phosphate group to ADP so that it reverts to ATP – ready to provide energy for working muscles.

It’s all about increasing the body’s capacity to make more energy, making the skeletal muscle work for a longer period of time. It works best in high intensity exercise when rapid bursts of energy are released.

As alluded to earlier, creatine is made up of three amino acids: arginine, glycine and methionine. Firstly, arginine and glycine combine to form guanidinoacetate under the influence of the enzyme arginine:glycine amidinotransferase. Next, methionine donates a methyl group (one carbon and three hydrogen atoms) in a two-step process involving the production of S-adenosylmethionine and its reaction with guanidinoacetate to form creatine, governed by the enzymes methionine adenosyltransferase and guanidinoacetate methyltransferase.

The molecule is osmotically active which increases intracellular water retention and protein synthesis, aiding their growth. It can also reduce muscular lactic acid build up.

Creatine can also enhance the ability of the muscles to contract. Muscle contraction requires the interaction of actin and myosin in a cyclic manner resulting in the shortening of the sarcomere (muscle cell). The initiation of muscle contraction requires calcium release which binds to troponin on the actin filament, revealing myosin attachment sites. The binding and subsequent movement of the myosin heads to the actin filament pulls it along, contracting the skeletal muscle. This process inevitably requires ATP which is supplied by creatine’s ability to increase mitochondrial ATP production and transportation to the myosin heads for the formation of this “cross bridge cycle”.

Side effects of creatine supplementation are rare and anecdotal at best. Clinical trials have revealed no compelling evidence with regards to adverse effects of creatine on the body if taken correctly. The timing, method of consumption and dose are important when taking creatine though.

We’ve seen how creatine, whether dietary or supplemental, can dramatically increase the working body’s reserve of ATP and as such, influence the outcome of exercise.

Now who wants tickets for the gun show?

Thanks for reading! Why not head over to Beauty by the Geeks to keep the science flowing?!

References

Bemben MG, & Lamont HS (2005). Creatine supplementation and exercise performance: recent findings. Sports medicine (Auckland, N.Z.), 35 (2), 107-25 PMID: 15707376

Brosnan JT, da Silva RP, & Brosnan ME (2011). The metabolic burden of creatine synthesis. Amino acids, 40 (5), 1325-31 PMID: 21387089

Cooper R, Naclerio F, Allgrove J, & Jimenez A (2012). Creatine supplementation with specific view to exercise/sports performance: an update. Journal of the International Society of Sports Nutrition, 9 (1) PMID: 22817979

Images adapted from:

http://www.beautybythegeeks.com/molecular-mondays-creatine/

http://ebsco.smartimagebase.com/actin-myosin-cross-bridge-cycle/view-item?ItemID=24926