Since the site is not ready yet, here's a fun fact:
Found abundantly in myocytes, creatine kinase (CK) is a protein that phosphorylates the small molecule creatine during a period of low muscle effort and excess ATP, allowing the myocyte to store energy in the form of phosphocreatine. As muscle activity increases and ATP levels deplete, the reaction is reversed and CK phosphorylates ADP using phosphocreatine, allowing ATP levels to equilibrate. Because of this, many athletes use creatine to give them that crucial edge (or extra pump) during intense training.
Easter egg: on the Biochem recruitment poster, the image of creatine kinase is accompanied by the words "Get pumped for biochemistry."