SPACI score report for 4kbb in ASTRAL 2.06:

PDB Entry: 4kbb
SPACI score: 0.39
AEROSPACI score: 0.39

Experiment type: XRAY
Resolution: 2.3
R-factor: 0.159
PCK1 PROCHECK Ramachandran: 1
PCK2 PROCHECK Chi-1 angle: 2
PCK3 PROCHECK H-bonds: 3
WCK1 WHAT_CHECK Packing: -0.973
WCK2 WHAT_CHECK Ramachandran: -0.788
WCK3 WHAT_CHECK Chi angles: -1.193
WCK4 WHAT_CHECK Backbone: 2.347

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).