SPACI score report for 3nbu in ASTRAL 2.08:

PDB Entry: 3nbu
SPACI score: 0.45
AEROSPACI score: 0.45

Experiment type: XRAY
Resolution: 2.05
R-factor: 0.172
PCK1 PROCHECK Ramachandran: 1
PCK2 PROCHECK Chi-1 angle: 1
PCK3 PROCHECK H-bonds: 2
WCK1 WHAT_CHECK Packing: -1.561
WCK2 WHAT_CHECK Ramachandran: -2.071
WCK3 WHAT_CHECK Chi angles: -1.438
WCK4 WHAT_CHECK Backbone: -0.659

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).