Purification, crystallization and preliminary X-ray analysis of Drosophilamelanogaster ferrochelatase

Ferrochelatase (protoheme ferrolyase, E.C. 4.99.1.1), the terminal enzyme i n the heme biosynthetic pathway, catalyzes the insertion of ferrous iron in to protoporphyrin IX to form protoheme. In eukaryotes, the protein is assoc iated with the inner surface of the inner mitochondrial membrane, and in hi gher animals the enzyme contains a [2Fe-2S] cluster. This cluster is highly sensitive to NO and is coordinated by four Cys residues whose spacing in t he primary sequence is unique. Ferrochelatase from Drosophila melanogaster has been expressed in Escherichia coli with an amino-terminal six-histidine tag and purified to homogeneity. The protein has been crystallized with th e [2Fe-2S] cluster intact. The crystals belong to space group I422, with un it-cell dimensions a = b = 158.1, c = 171.2 Angstrom and two molecules in t he asymmetric unit, and diffract to 3.0 Angstrom resolution.