K. Sekar et al., 1.72 ANGSTROM RESOLUTION REFINEMENT OF THE TRIGONAL FORM OF BOVINE PANCREATIC PHOSPHOLIPASE A(2), Acta crystallographica. Section D, Biological crystallography, 54, 1998, pp. 342-346
Citations number
24
Categorie Soggetti
Crystallography,"Biochemical Research Methods",Biophysics,Biology
The trigonal crystal structure of the recombinant bovine pancreatic ph
ospholipase A(2) has been re-refined at a slightly higher resolution (
1.72 Angstrom). The crystals are trigonal, space group P3(1)21, unit-c
ell parameters a = b = 46.78 and c = 102.89 Angstrom and are isomorpho
us to the previous structure. The structure was refined to a final cry
stallographic R value of 19.5% (R-free = 28.4%) using 10 531 reflectio
ns. A total of 106 solvent molecules were included in the refinement c
ompared with the earlier refinement which contains only 85 water molec
ules and 8 925 reflections at 1.8 Angstrom resolution. The root-mean-s
quare deviation from the ideal bond lengths and bond angles is conside
rably better in the present refinement. The active site is extended (s
imilar to 14 Angstrom) from Ala1 to the calcium. The three catalytic r
esidues (Asp99, His48 and the catalytic water) are connected by the co
nserved structural water and the N-terminal Ala1 on one side, and by t
he calcium through an equatorial water on the other. The water molecul
es play a role in the activity of the enzyme PLA2. The Ala1 end of the
extended active site performs the activation of the phospholipid memb
ranes while the opposite end performs the hydrolysis of the monomeric
phospholipids.