IMPROVED PURIFICATION, CRYSTALLIZATION AND PRIMARY STRUCTURE OF PYRUVATE-FERREDOXIN OXIDOREDUCTASE FROM HALOBACTERIUM-HALOBIUM

An improved purification procedure, including nickel chelate affinity chromatography, is reported which resulted in a crystallizable pyruvate: ferredoxin oxidoreductase preparation from Halobacterium halobium. Crystals of the enzyme were obtained using potassium citrate as the precipitant. The genes coding for pyruvate: ferredoxin oxidoreductase were cloned and their nucleotide sequences determined. The genes of both subunits were adjacent to one another on the halobacterial genome. The derived amino acid sequences were confirmed by partial primary structure analysis of the purified protein. The structural motif of thiamin-diphosphate-binding enzymes was unequivocally located in the deduced amino acid sequence of the small subunit.