Abstract
The ability to perform the very simple oxidation of two molecules of thiosulfate to tetrathionate is widespread among prokaryotes. Despite the prevalent occurrence of tetrathionate formation and its well documented significance within the sulfur cycle, little is known about the enzymes that catalyze the oxidative condensation of two thiosulfate anions. To fill this gap, the thiosulfate dehydrogenase (TsdA) enzyme from the purple sulfur bacterium Allochromatium vinosum was recombinantly expressed in Escherichia coli, purified and crystallized, and a crystallographic data set was collected. The crystals belonged to the monoclinic space group C2, with unit-cell parameters a = 79.2, b = 69.9, c = 57.9 Å, β = 129.3°, contained one monomer per asymmetric unit and diffracted to a resolution of 1.98 Å.