SPACI score report for 1rb5 in ASTRAL 1.67:

PDB Entry: 1rb5
SPACI score: 0.51
AEROSPACI score: -1.49 (mutant; see below)

Experiment type: XRAY
Resolution: 1.9
R-factor: 0.205
PCK1 PROCHECK Ramachandran: 1
PCK2 PROCHECK Chi-1 angle: 1
PCK3 PROCHECK H-bonds: 1
WCK1 WHAT_CHECK Packing: 5.714
WCK2 WHAT_CHECK Ramachandran: 3.163
WCK3 WHAT_CHECK Chi angles: 1.914
WCK4 WHAT_CHECK Backbone: 2.291

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