[ccp4bb] how to model an average of two different amino acids at the same position in a crystal structure

[Seema Mittal]

Hi All,

I have a structure where electron density shows that the complex  
crystallized is not in a unique conformation in the crystal lattice.  
It seems the electron density is an average of two possible  
orientations of the same complex.

Since, the protein is bound to its substrate as a dimer, where the  
sequence of the two monomers (forming the dimer) is different at only  
a couple of positions, two different amino acids can be built in the  
same electron density. For example, serine vs alanine.
From our previous experience in crystallizing the same complex, we  
know that its an averaged density. I am wondering what is the most  
accurate and acceptable way to represent it in the actual pdb file  
without complicating the analysis.

I am hoping to resolve this issue by getting some inputs from this  
expert community.

Thanks in advance,

Best,
Seema Mittal

Graduate Research Assistant,
Department of Biochemistry & Molecular Pharmacology,
970L Lazare Research Building,
University of Massachusetts Medical School,
364 Plantation Street,
Worcester, MA 01605