SPACI score report for 1z4n in ASTRAL 2.07:

PDB Entry: 1z4n
SPACI score: 0.44
AEROSPACI score: 0.44

Experiment type: XRAY
Resolution: 1.97
R-factor: 0.207
PCK1 PROCHECK Ramachandran: 1
PCK2 PROCHECK Chi-1 angle: 1
PCK3 PROCHECK H-bonds: 2
WCK1 WHAT_CHECK Packing: -0.761
WCK2 WHAT_CHECK Ramachandran: -1.031
WCK3 WHAT_CHECK Chi angles: -0.863
WCK4 WHAT_CHECK Backbone: 0.65

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).