The X-ray structure of phospholipase A₂. The enzyme from cobra venom is shown in cyan wireframe complexed with an acylamino phospholipid analog in its active site shown space-filling form with C gray, O red, P orange and S yellow. A Ca²⁺ ion in the active site is shown in magenta. Click on the [Show Hydrophobic Pocket] button to show the space-filling form of the hydrophobic pocket in yellow with other hydrophobic amino acids colored red. [Courtesy of Edward A. Dennis, University of California at San Diego. PDBid 1AYP]