SPACI score report for 1zkg in ASTRAL 2.08:

PDB Entry: 1zkg
SPACI score: 0.39
AEROSPACI score: 0.39

Experiment type: XRAY
Resolution: 2.3
R-factor: 0.204
PCK1 PROCHECK Ramachandran: 1
PCK2 PROCHECK Chi-1 angle: 1
PCK3 PROCHECK H-bonds: 1
WCK1 WHAT_CHECK Packing: -0.206
WCK2 WHAT_CHECK Ramachandran: -1.527
WCK3 WHAT_CHECK Chi angles: -2.043
WCK4 WHAT_CHECK Backbone: 5.562

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).