4.2.3.19	purified recombinant wild-type enzyme in apo form or in complex with inhibitor BPH-629, mutant D75C in complex with substrate ent-copalyl diphosphate, sitting drop vapor diffusion method, mixing of 6.4 mg/ml protein in 25 mM Tris, pH 7.5, and 150 mM NaCl with reservoir solution containing 0.7 M ammonium tartrate dibasic, pH 7.0 and 2-4% w/v PEG 4000 for the wild-type enzyme, for the inhibitor BPH-629 complex, the enzyme solution also contains 1 mM MgCl2, 10 mM DTT, and 2.5 mM BPH-629, for the substrate complex, the D75C mutant crystal is prepared under the same crystallization conditions, then soaked with the cryo-protectant containing 5 mM ent-copalyl diphosphate for 5 hours, 2-3 days, room temperature, X-ray diffraction structure determination and analysis at 1.80-2.34 A resolution	749301