Crystallization and preliminary X‐ray crystallographic studies of a Lys49‐phospholipase A 2 homologue from Bothrops pirajai venom complexed with rosmarinic acid

PrTX‐I, a noncatalytic and myotoxic Lys49‐phospholipase A 2 from Bothrops pirajai venom, was crystallized in the presence of the inhibitor rosmarinic acid (RA). This is the active compound in the methanolic extract of Cordia verbenacea , a plant that is largely used in Brazilian folk medicine. The crystals diffracted X‐rays to 1.8 Å resolution and the structure was solved by molecular‐replacement techniques, showing electron density that corresponds to RA molecules at the entrance to the hydrophobic channel. The crystals belong to space group P 2 1 2 1 2 1 , indicating conformational changes in the structure after ligand binding: the crystals of all apo Lys49‐phospholipase A 2 structures belong to space group P 3 1 21, while the crystals of complexed structures belong to space groups P 2 1 or P 2 1 2 1 2 1 .