Where employed, coordination of the Zn1 (by Glu246 OE2, Thr285 OD1, Asp465 OD1 and His466 NE2) and Zn2 (by His395 NE2 and His478 NE2) zinc ions was restrained to the distances observed in the crystal structure 5LRM , and the pairwise angles between them (set to reference value ± 10.0°) with restraint values of 25 kcal mol -1 Å 2 .