SPACI score report for 4o21 in ASTRAL 2.04:

WARNING! The SPACI score for this entry is not valid. The PROCHECK parameters for this entry could not be obtained, and poor results have been arbitrarily assumed.

PDB Entry: 4o21
SPACI score: 0.41 (not valid)
AEROSPACI score: 0.41 (not valid)

Experiment type: XRAY
Resolution: 1.95
R-factor: 0.17
PCK1 PROCHECK Ramachandran: N/A
PCK2 PROCHECK Chi-1 angle: N/A
WCK1 WHAT_CHECK Packing: -1.262
WCK2 WHAT_CHECK Ramachandran: -0.564
WCK3 WHAT_CHECK Chi angles: 0.389
WCK4 WHAT_CHECK Backbone: 3.363

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).