SPACI score report for 1st6 in ASTRAL 2.08:

PDB Entry: 1st6
SPACI score: 0.08
AEROSPACI score: 0.08

Experiment type: XRAY
Resolution: 3.1
R-factor: 0.316
PCK1 PROCHECK Ramachandran: 1
PCK2 PROCHECK Chi-1 angle: 2
PCK3 PROCHECK H-bonds: 3
WCK1 WHAT_CHECK Packing: -2.367
WCK2 WHAT_CHECK Ramachandran: -7.602
WCK3 WHAT_CHECK Chi angles: -3.998
WCK4 WHAT_CHECK Backbone: -1.624

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).