SPACI score report for 1usg in ASTRAL 1.75:

PDB Entry: 1usg
SPACI score: 0.74
AEROSPACI score: 0.74

Experiment type: XRAY
Resolution: 1.53
R-factor: 0.191
PCK1 PROCHECK Ramachandran: 1
PCK2 PROCHECK Chi-1 angle: 1
PCK3 PROCHECK H-bonds: 1
WCK1 WHAT_CHECK Packing: -0.849
WCK2 WHAT_CHECK Ramachandran: 0.027
WCK3 WHAT_CHECK Chi angles: 0.485
WCK4 WHAT_CHECK Backbone: -0.172

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).