Crystallization and preliminary crystallographic study of an extremophile cytochrome c4 from Thiobacillus ferrooxidans.
Soluble periplasmic dihaemic cytochrome c(4), of 21 293 Da molecular mass, has been characterized from Thiobacillus ferrooxidans, an acidophilic bacteria. The native cytochrome has been purified from the bacteria using ion-exchange chromatography and crystallized using solution 27 of the Hampton Research Crystal Screen II. The crystals belong to the hexagonal space group P6(2)22 or P6(4)22, with unit-cell parameters a = 101.59, b = 101.59, c = 151.59 A. Frozen crystals diffract to 2.17 A resolution. The MAD method is currently being used (four Fe atoms per asymmetric unit) to solve the protein structure.