Open AccessEvaluation of macromolecular electron‐density map quality using the correlation of local r.m.s. density
Author(s) -
Terwilliger Thomas C.,
Berendzen Joel
Publication year - 1999
Publication title -
acta crystallographica section d
Language(s) - English
Resource type - Journals
ISSN - 1399-0047
DOI - 10.1107/s090744499901029x
Subject(s) - measure (data warehouse) , electron density , statistic , chemistry , correlation , macromolecule , electron , physics , mathematics , statistics , quantum mechanics , data mining , geometry , computer science , biochemistry
It has recently been shown that the standard deviation of local r.m.s. electron density is a good indicator of the presence of distinct regions of solvent and protein in macromolecular electron‐density maps [Terwilliger & Berendzen (1999). Acta Cryst. D 55 , 501–505]. Here, it is demonstrated that a complementary measure, the correlation of local r.m.s. density in adjacent regions on the unit cell, is also a good measure of the presence of distinct solvent and protein regions. The correlation of local r.m.s. density is essentially a measure of how contiguous the solvent (and protein) regions are in the electron‐density map. This statistic can be calculated in real space or in reciprocal space and has potential uses in evaluation of heavy‐atom solutions in the MIR and MAD methods as well as for evaluation of trial phase sets in ab initio phasing procedures.