Caffeine: Difference between revisions

The A2A receptor improves the flow of blood to the heart, increasing heart rate, and additionally can lower blood pressure. When adenosine binds to the A2A receptor, cyclicAMP levels increase, and ERK1/ERK2 levels increase (Antonioli, et. al., 2013).

The adenosine receptor (A2A) is a G-protein coupled receptor, which is a transmembrane protein that consists of secondary structures, such as seven alpha helical domains. Inside the third and seventh transmembrane helical domains, there are hydrophobic side chains that are required for ligand recognition. The target ligand, adenosine, is a large, polar molecule that binds to the extracellular binding domain of the A2A receptor by several nonpolar interactions. To be specific, these nonpolar interactions include hydrogen bonding (11), aromatic stacking interactions (1), and many van der Waals interactions (Xu et. al, 2011). To avoid the steric interactions between the ribose ring of adenosine and the tryptophan of the enzyme binding pocket, these nonpolar interactions cause conformational changes within the binding cavity, and cause an internal rotation and tilt of the seventh helical domain (Xu et. al, 2011). Other molecules, such as caffeine can also bind to these adenosine receptors. When caffeine binds to this receptor, it inhibits adenosine from binding to the extracellular binding domain of the A2A receptor.