Structure of ECP in complex with citrate ions at 1.50 Angstroms

Three-dimensional crystal structure of human eosinophil cationic protein (RNase 3) at 1.75 A resolution.

The sulfate-binding site structure of the human eosinophil cationic protein as revealed by a new crystal form.

MRPPQFTRAQWFAIQHISLNPPRCTIAMRAINNYRWRCKNQNTFLRTTFANVVNVCGNQSIRCPHNRTLNNCHRSRFRVP
LLHCDLINPGAQNISNCRYADRPGRRFYVVACDNRDPRDSPRYPVVPVHLDTTI

Protein resuspended in sodium cacodylate buffer (20mM, pH5.0). 1 uL of protein sample was mixed with 1 uL of crystallisation buffer (0.1M sodium citrate pH5.2, 8% Jeffamine M-600, 10mM iron(III) chloride)

ECP in complex with citrate ions at 1.7 A resolution

ECP/H15A mutant in complex with citrate and iron ions

AUTHORS STATE THAT BOTH IRON AND CITRATE ATOMS HAVE BEEN ADJUSTED TO THE CORRESPONDING ELECTRON DENSITY. CIT302 SURROUNDS THE SAME-CHAIN IRON ATOM, WHICH CAN ALSO COORDINATE SOME SURROUNDING WATER MOLECULES. THESE HAVE BEEN DIFFICULT TO ADJUST AS THE ELECTRON DENSITY AROUND THE IRON ATOMS IS NOT SPHERICAL AND THE WATER MOLECULES THERE WOULD NOT HAVE A DEFINED FIXED POSITION. THE SURROUNDING CITRATE LIGAND ALSO SHOWED HIGH MOBILITY. THESE PROBLEMS ALTOGETHER MAKE REFINEMENT STEPS MOVE THE CITRATE LIGAND IN SUCH A POSITION THAT CLASHES APPEARED.

RNase 3, Eosinophil Cationic Protein (ECP), HYDROLASE

RPPQFTRAQWFAIQHISLNPPRCTIAMRAINNYRWRCKNQNTFLRTTFANVVNVCGNQSIRCPHNRTLNNCHRSRFRVPL
LHCDLINPGAQNISNCTYADRPGRRFYVVACDNRDPRDSPRYPVVPVHLDTTI