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?
