PRISM - APPLICATION TO THE SOLUTION OF 2 PROTEIN STRUCTURES

Citation
C. Bystroff et al., PRISM - APPLICATION TO THE SOLUTION OF 2 PROTEIN STRUCTURES, Acta crystallographica. Section D, Biological crystallography, 49, 1993, pp. 440-448
Citations number
20
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Crystallography,Biology,"Pharmacology & Pharmacy
ISSN journal
0907-4449
Volume
49
Year of publication
1993
Part
5
Pages
440 - 448
Database
ISI
SICI code
0907-4449(1993)49:<440:P-ATTS>2.0.ZU;2-E
Abstract
The previous paper described a phase-refinement strategy for protein c rystallography which exploited the information that proteins consist o f connected linear chains of atoms. Here the method is applied to a mo lecular-replacement problem, the structure of the protease inhibitor e cotin bound to trypsin, and a single isomorphous replacement problem, the structure of the N-terminal domain of apolipoprotein E. The starti ng phases for the ecotin-trypsin complex were based on a partial model (trypsin) containing 61 % of the atoms in the complex. Iterative skel etonization gave better results than either solvent flattening or twof old non-crystallographic symmetry averaging as measured by the reducti on in the free R factor [Brunger (1992). Nature (London), 355, 472-474 ]. Protection of the trypsin density during the course of the refineme nt greatly improved the performance of both skeletonizing and solvent flattening. In the case of apolipoprotein E, previous attempts using s olvent flattening had failed to improve the SIR phases to the point of obtaining an interpretable map. The combination of iterative skeleton ization and solvent flattening decreased the phase error with respect to the final refined structure, significantly more than solvent flatte ning alone. The final maps generated by the skeletonization procedure for both the ecotin-trypsin complex and apolipoprotein E were readily interpretable.