SPACI score report for 1x91 in ASTRAL 2.07:

PDB Entry: 1x91
SPACI score: 0.65
AEROSPACI score: 0.65 (mutant; see below)

Experiment type: XRAY
Resolution: 1.5
R-factor: 0.185
PCK1 PROCHECK Ramachandran: 1
PCK2 PROCHECK Chi-1 angle: 1
PCK3 PROCHECK H-bonds: 1
WCK1 WHAT_CHECK Packing: 0.244
WCK2 WHAT_CHECK Ramachandran: 2.538
WCK3 WHAT_CHECK Chi angles: -0.333
WCK4 WHAT_CHECK Backbone: 1.698

The AEROSPACI score for this entry is lower than the SPACI score because human-curated comments on the entry in SCOPe contain the phrase mutant. The full comment is: "mutant"

Note: Here are links to pages about PROCHECK and WHAT_CHECK.

Here is the full WHAT_CHECK report on this protein (linked from the WHAT_CHECK site).