Crystallization and preliminary X-ray analysis of Escherichia coli p20, a novel thiol peroxidase.

Escherichia coli p20 is a thioredoxin-dependent thiol peroxidase. This protein represents a novel group of antioxidant enzymes that are widely expressed in various pathogenic bacteria and show distant yet significant sequence homology with peroxiredoxins. E. coli p20, overexpressed in E. coli, was crystallized with PEG 4000 and 2-propanol as precipitants using the hanging-drop vapour-diffusion method. Diffraction data were collected to 2.2 A resolution using synchrotron radiation. The crystals belong to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 38.97, b = 58.97, c = 127.59 A. The asymmetric unit contains two p20 molecules, with a corresponding V(M) of 2.06 A(3) Da(-1) and a solvent content of 40.4%.