I am working on a model at a resolution of 2.1 A. The active site Cys in both copies have a positive density towards the S end of the residue and these blobs are there in FEM and Polder maps. When I replace these residues with either CSS or SMC, I get the following statistics. What is the best way of deciding which one is correct?
CSS: R/Rfree - 0.2016/0.2299 Local CC (chain A/B) - 0.950/0.937 Bfactor (chain A N/CA/C/O/CB/SG/SD) - 42.8/48.6/46.7/42.8/57.3/66.2/98.8 Bfactor (chain B N/CA/C/O/CB/SG/SD) -42.0/44.5/47.2/45.7/57/60.3/95.3 No residual positive density left. SMC: R/Rfree - 0.2087/0.2299 Local CC (chain A/B) - 0.903/0.886 Bfactor (chain A N/CA/C/O/CB/SG/CS) - 43.9/47.9/46.5/42.1/51.8/64.4/66.5 Bfactor (chain A N/CA/C/O/CB/SG/CS) - 43.4/45.0/47.3/45.4/51.8/59.4/66.1 Crescent shaped positive density left towards the CS atom end. Although CSS seems more plausible, the high B factors of SD make me wonder if they are correct. Thanks. Mohamed
