Ab initio structure determination of the triple mutant (K53,56,121M) of bovine pancreatic phospholipase A2 at atomic and high resolution using ACORN

摘要

Atomic resolution (0.97 A) data were collected for the triple mutant (K53,56,121M) of bovine pancreatic phospholipase A2 at 100 K and data extending to 1.0 A resolution were used for the present study. Accuracy of the data at high resolution allowed the structure to be solved using the program ACORN, with a random single-atom start in an ab initio manner. The phases obtained from ACORN are of good quality and revealed most of the amino acid residues. Single wavelength Anomalous Diffraction (SAD) datawere also used to locate the position of the sulphurs and ACORN was run with these atomic positions as a source of phasing information. The effect of truncating the data to 1.4 and 1.45 A for input to ACORN is also examined. Larger fragments are required to trigger successful phase refinement at these lower resolutions.