SPACI score report for 3zn1 in ASTRAL 2.06:

PDB Entry: 3zn1
SPACI score: 0.23
AEROSPACI score: 0.23

Experiment type: XRAY
Resolution: 3.1
R-factor: 0.21081
PCK1 PROCHECK Ramachandran: 1
PCK2 PROCHECK Chi-1 angle: 2
PCK3 PROCHECK H-bonds: 2
WCK1 WHAT_CHECK Packing: -0.525
WCK2 WHAT_CHECK Ramachandran: -2.036
WCK3 WHAT_CHECK Chi angles: -2.863
WCK4 WHAT_CHECK Backbone: 3.463

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).