Expression, purification, crystallization and preliminary X‐ray diffraction crystallographic study of PurH from Escherichia coli

In bacteria and eukaryotes, the last two steps of de novo purine biosynthesis are catalyzed by bifunctional purine‐biosynthesis protein (PurH), which is composed of two functionally independent domains linked by a flexible region. The N‐terminal domain possesses IMP cyclohydrolase activity and the C‐terminal domain possesses aminoimidazole‐4‐carboxamide ribonucleotide transformylase activity. This study reports the expression, purification, crystallization and preliminary X‐ray crystallographic analysis of PurH from Escherichia coli with an N‐terminal His 6 tag. The crystals diffracted to a maximum resolution of 3.05 Å and belonged to the monoclinic space group P 2 1 , with unit‐cell parameters a = 76.37, b = 132.15, c = 82.64 Å, β = 111.86°.