Hi Seema, Couple scenarios plausible (i) mutant is "super slow" compared to WT that crystallization was setup prior to any significant reaction and / or (ii) components, as well the pH, of crystallization condition made the reaction even more slower. Of course, if the reaction has partially occurred, you are likely to observe occupancy less than 1. These plausible only scenarios!!
Hope this helps, Partha On Fri, May 26, 2017 at 4:59 PM Seema H Irani <[email protected]> wrote: > I crystallized a PLP dependent enzyme and wanted to capture the enzyme > substrate complex, however due high activity of the enzyme I could see no > density at the active site upon soaking with the substrate. I hence made a > bunch of mutants of the active site residues and one of them showed density > consistent with the substrate in some of the molecules in the asymmetric > unit. Surprisingly however when I measured the activity of this mutant it > had 30% of the wildtype activity I am wondering why is it still possible > for me to see substrate density for this mutant? > > >
