Crystallization and preliminary X-ray analysis of the NAD + -reducing (NiFe) hydrogenase from Hydrogenophilus thermoluteolus TH-1

NAD+-reducing [NiFe] hydrogenases catalyze the oxidoreduction of dihydrogen concomitant with the interconversion of NAD+ and NADH. Here, the isolation, purification and crystallization of the NAD+-reducing [NiFe] hydrogenase from Hydrogenophilus thermoluteolus TH-1 are reported. Crystals of the NAD+-reducing [NiFe] hydrogenase were obtained within one week from a solution containing polyethylene glycol using the sitting-drop vapour-diffusion method and micro-seeding. The crystal diffracted to 2.58 A resolution and belonged to space group C2, with unit-cell parameters a = 131.43, b = 189.71, c = 124.59 A, β = 109.42°. Assuming the presence of two NAD+-reducing [NiFe] hydrogenase molecules in the asymmetric unit, VM was calculated to be 2.2 A3 Da−1, which corresponds to a solvent content of 43%. Initial phases were determined by the single-wavelength anomalous dispersion method using the anomalous signal from the Fe atoms.