Purification and characterization of chicken erythrocyte ferrochelatase

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Abstract
Ferrochelatase (EC 4.99.1.1) was purified 2000-fold to apparent homogeneity from isolated chicken erythrocyte mitochondria. The purified enzyme yields a single band on sodium dodecyl sulfate/polyacrylamide-gel electrophoresis with an apparent MW of 42,000. The enzyme uses proto-, meso- and deutero-porphyrin with Km values of 37, 51 and 80 .mu.M, respectively. The disubstituted porphyrins 2,4-bisglycol deuteroporphyrin and 2,4-disulfonic deuteroporphyrin were not substrates. Mn2+, Hg2+, Pb2+ and Co2+ were strong inhibitors of the purified enzyme. Palmitic acid and oleic acid stimulated activity; linoleic acid inhibited and phospholipids had variable effects. Chicken ferrochelatase was inhibited by N-ethylmaleimide and iodoacetamide. Inhibition by iodoacetamide was pseudo-1st-order, but inhibition by N-ethylmaleimide appeared to be biphasic in nature with an initial high rate followed by a much lower rate of inactivation. The characteristics of the chicken erythrocyte enzyme are compared with those previously reported for mammalian liver ferrochelatase.

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