Hi, It occurs quite frequently with renin for example, with two molecules in the asu. Depending on the affinity and shape of the inhibitors both, only one or neither of the sites may be occupied. The slight, but significant conformational difference between the two crystallographically independent molecules certainly contribute to this observation.
Regards, Zsolt Zsolt Bocskei sanofi-aventis Structure Design and Informatics 16 rue d'Ankara 67000 Strasbourg France tel: +33 632326710 -----Original Message----- From: CCP4 bulletin board [mailto:ccp...@jiscmail.ac.uk] On Behalf Of ANDY DODDS Sent: Tuesday, June 01, 2010 12:22 PM To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] Ligand present in only one monomer in NCS Hello, I am solving a structure of an enzyme, which crystallises as a dimer. We have pretty good evidence that this operates as a dimer in vitro, also. We have an inhibitor of this enzyme, which we are keen to visualise by X-ray methods. We seem to have very strong density in which we can model our inhibitor, with good stats and no negative density. However, there is only density in one of the monomers, nothing in the other. The SG is P212121, and although I can postulate why this may have happened (if this is indeed what HAS happened), different solvent channel accessibility etc., I would like to know how common this was and, if possible, some literature regarding this, if the board would be so kind? Regards, Andrew.
