Metal binding to porcine pancreatic elastase: calcium or not calcium.
Porcine pancreatic elastase has been crystallized at slightly acidic pH under two similar but slightly different conditions. Diffraction data were collected at a wavelength of 1.5 A to a maximum resolution of 1.7 A. Both difference electron-density maps and anomalous difference electron-density maps suggest that in crystals grown from a sodium sulfate solution PPE binds Na(+) in its metal-binding site. In contrast, PPE binds Ca(2+) in crystals grown from a solution containing sodium citrate and calcium chloride. This observation is in contradiction to most PPE structures reported in the PDB. In addition to the metal-binding site, up to three other binding sites, which appear to be anion-binding sites, could be identified based on the observed anomalous intensity differences.
EMBL Hamburg Outstation, c/o DESY, Notkestrasse 85, D-22603 Hamburg, Germany. msweiss@embl-hamburg.de
Manfred S
MS
Weiss
Santosh
S
Panjikar
Elzbieta
E
Nowak
Paul A
PA
Tucker
D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism*; D008670:Metals / Q000378:metabolism*; D008958:Models, Molecular; D010196:Pancreatic Elastase / Q000378:metabolism*; D011485:Protein Binding; D013552:Swine
D008670:Metals; D010196:Pancreatic Elastase; D002118:Calcium