Hi, Long crystallization times and irreproducibility together with missing residues points strongly to some slow proteolysis in your crystal drops that eventually generated a crystallizable fragment. A lot of people actually do this on purpose by adding proteases to generate stable fragments. Here's <http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0005094> one example paper that came up from quick googling but there are lots of others you can find in the literature.
Tom On Fri, Mar 9, 2018 at 3:25 PM, Rajesh < 00001642be9504b8-dmarc-requ...@jiscmail.ac.uk> wrote: > Dear BB, > > I apologize for the off topic. But I strongly believe this is the right > place to ask my question. > > We are working on a protein that is 300 amino acids in length. After many > efforts, we could solve the structure at 1.60 Å resolution. It took > almost 10 months to get this crystal and we could not reproduce it. The > maps are interpretable and we could model only till residue 190 and we > could not see any density for the rest of the molecule. My question is- > Does anyone has encountered such a structure with lots of missing density? > I would appreciate your efforts if someone can send me few references > describing such type of structures. Is there any chance that microbes can > cleave the protein in the crystal drops? > > > > > > Thanks, > > Rajesh.. > >
