SPACI score report for 1zkc in ASTRAL 2.07:

PDB Entry: 1zkc
SPACI score: 0.6
AEROSPACI score: 0.6

Experiment type: XRAY
Resolution: 1.65
R-factor: 0.158
PCK1 PROCHECK Ramachandran: 1
PCK2 PROCHECK Chi-1 angle: 1
PCK3 PROCHECK H-bonds: 2
WCK1 WHAT_CHECK Packing: -0.799
WCK2 WHAT_CHECK Ramachandran: -0.25
WCK3 WHAT_CHECK Chi angles: 1.621
WCK4 WHAT_CHECK Backbone: -0.336

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).