Reprinted by permission from Nature
Kiefer et al. Nature 405, 97-101 (2000)
Nature

Arachidonate and prostaglandin bound to the cyclooxygenase active site of wild-type COX-2. a, Stereo image of the experimental difference electron density map  before the inclusion of AA (green trace) or PGH₂ (gold trace)  b, Diagram of PGH₂ (gold) and AA (cyan) bound to the cyclooxygenase active site. Mobile side chains are coloured gold and cyan to match their PGH ₂ and AA bound positions, respectively.

Notice the hydrophobic nature of the amino acids surrounding the arachidonic acd.  Note as well the kinks in the arachidonic acid associated with 4 all-cis double bonds in the fatty acid.