SPACI score report for 4gb2 in ASTRAL 2.08:

PDB Entry: 4gb2
SPACI score: 0.53
AEROSPACI score: 0.53

Experiment type: XRAY
Resolution: 1.79
R-factor: 0.176
PCK1 PROCHECK Ramachandran: 1
PCK2 PROCHECK Chi-1 angle: 1
PCK3 PROCHECK H-bonds: 2
WCK1 WHAT_CHECK Packing: 0.345
WCK2 WHAT_CHECK Ramachandran: -2.054
WCK3 WHAT_CHECK Chi angles: 1.163
WCK4 WHAT_CHECK Backbone: 2.779

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).