SPACI score report for 2rkn in ASTRAL 2.08:

PDB Entry: 2rkn
SPACI score: 0.57
AEROSPACI score: 0.57

Experiment type: XRAY
Resolution: 1.6
R-factor: 0.192
PCK1 PROCHECK Ramachandran: 1
PCK2 PROCHECK Chi-1 angle: 1
PCK3 PROCHECK H-bonds: 2
WCK1 WHAT_CHECK Packing: -3.194
WCK2 WHAT_CHECK Ramachandran: 0.156
WCK3 WHAT_CHECK Chi angles: -2.426
WCK4 WHAT_CHECK Backbone: 4.6

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).