SPACI score report for 4k8b in ASTRAL 2.03:

WARNING! The SPACI score for this entry is not valid. The PROCHECK parameters for this entry could not be obtained, and poor results have been arbitrarily assumed.

PDB Entry: 4k8b
SPACI score: 0.2 (not valid)
AEROSPACI score: 0.2 (not valid)

Experiment type: XRAY
Resolution: 2.8
R-factor: 0.204
PCK1 PROCHECK Ramachandran: N/A
PCK2 PROCHECK Chi-1 angle: N/A
PCK3 PROCHECK H-bonds: N/A
WCK1 WHAT_CHECK Packing: -1.613
WCK2 WHAT_CHECK Ramachandran: -2.187
WCK3 WHAT_CHECK Chi angles: -5.005
WCK4 WHAT_CHECK Backbone: 2.495

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).