SPACI score report for 1zk4 in ASTRAL 2.03:

PDB Entry: 1zk4
SPACI score: 1.01
AEROSPACI score: 1.01

Experiment type: XRAY
Resolution: 1
R-factor: 0.159
PCK1 PROCHECK Ramachandran: 1
PCK2 PROCHECK Chi-1 angle: 1
PCK3 PROCHECK H-bonds: 1
WCK1 WHAT_CHECK Packing: 1.062
WCK2 WHAT_CHECK Ramachandran: -1.182
WCK3 WHAT_CHECK Chi angles: 0.058
WCK4 WHAT_CHECK Backbone: 4.162

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).