Expression, purification, crystallization and preliminary X-ray diffraction analysis of EtFPOX from Eupenicillium terrenum sp

The flavoenzyme fructosyl peptide oxidase (FPOX) catalyses the oxidative deglycation of fructosyl amino acids or fructosyl dipeptides to produce amino acids, glucosone and hydrogen peroxide. In this study, FPOX protein from Eupenicillium terrenum sp. (EtFPOX) was expressed in Escherichia coli and purified by Ni‐affinity and gel‐filtration chromatography. EtFPOX crystals were obtained using the sitting‐drop vapour‐diffusion method with polyethylene glycol 3350 as precipitant. X‐ray diffraction data were collected to 1.90 Å resolution using a synchrotron‐radiation source. The crystals belonged to space group P212121, with unit‐cell parameters a = 65.6, b = 80.0, c = 83.4 Å, and contained one molecule in the asymmetric unit. The calculated Matthews coefficient and solvent content were 2.22 Å3 Da−1 and 44.62%, respectively.