I just ran into something that might be a small bug (phenix 1.10.1-2155) Background: I have a problem data set for which the unit cell is too small to hold we thought we were crystallizing (which probably means we crystallized the wrong protein). In any case, I ran the data through Xtriage, supplying the sequence file for the too-large protein, even though I knew this is probably not correct. This sequence file contains 264 residues. I was surprised to see that the program returned with a perfectly reasonable estimate of the Matthews coefficient, making me briefly hopeful that I had been doing the calculation incorrectly. Alas, not so; when I dig through the log file, I find the following: ____begin excerpt_______________________________________________________________ determining composition from sequence file /xxxx/seq.dat Too many residues to fit in the ASU resetting numer of residues in monomer to 26 =================== Solvent content and Matthews coefficient ================== Crystallized molecule(s) defined as 264 protein residues ------------------------------------------------------------------- | Solvent content analysis | |-----------------------------------------------------------------| | Copies | Solvent content | Matthews coeff. | P(solvent content) | |-----------------------------------------------------------------| | 1 | 0.666 | 3.68 | 0.621 | | 2 | 0.331 | 1.84 | 0.379 | ------------------------------------------------------------------- Best guess : 1 copy in the ASU _____end excerpt_______________________________________________________________ So it seems as though the program, when confronted with a protein mass that’s too large for the AU, divides the mass by 10 and tries again. However, this is not clear from the results; in the results section, it states “Crystallized molecule(s) defined as 264 protein residues." So a user might be misled into thinking that everything is OK, when in fact it’s not… Cheers, Pat --------------------------------------------------------------------------------------- Patrick J. Loll, Ph. D. Professor of Biochemistry & Molecular Biology Director, Biochemistry Graduate Program Drexel University College of Medicine Room 10-102 New College Building 245 N. 15th St., Mailstop 497 Philadelphia, PA 19102-1192 USA (215) 762-7706 [email protected]