Is there really any notable structural difference between the keto and
forms? Differences between single/double bond lengths are so small,
probably not worth it unless you have very high resolution.
To do so, look at examples for multiple conformations. You need
a few "constraints interactions" statements to keep thw two forms
from interacting with each other. You can refine grouped occupancies
for the two substrate forms with "optimize group q=()..." but you
can't constrain the sum to be 1 or <=1. Also, with B and occupoancies
correlated, I usually adjust the average B's of the two conformations
to be equal before doing occupancy refinement.
Jodi Lubetsky wrote:
>> dear users,
>> I am refining a structure of an enzyme complexed to its substrate/product. THe
> enzyme catalyzes the conversion between the keto and enol forms, and both fit
> into my SA-omit map electron density. I was wondering how i would go about
> further refinement including both forms in my coordinates. Additionally, is
> there a way to also refine the occupancies of both forms?
>> thanks in advance,