Purification and properties of ferrochelatase from the yeast Saccharomyces cerevisiae. Evidence for a precursor form of the protein.

摘要: Ferrochelatase was purified to homogeneity from yeast mitochondrial membranes and found be a 40-kDa polypeptide with pI at 6.3. Fatty acids were absolutely necessary measure the activity in vitro. The Michaelis constants for protoporphyrin IX (9 x 10(-8) M), ferrous iron (1.6 10(-7) zinc 10(-6) M) determined on enzyme preparations presence of dithiothreitol. However, Km lower when measured absence dithiothreitol (K-m(Zn2+) = 2.5 M, Km(protoporphyrin) unchanged). maximum velocities 35,000 nmol heme/h/mg protein 27,000 zinc-protoporphyrin/h/mg protein. Antibodies against ferrochelatase raised rabbits used studies biogenesis enzyme. is synthesized as higher molecular weight precursor (Mr 44,000) that very rapidly matured vivo Mr 40,000 membrane-bound form. This form immunoprecipitated vitro translation (in rabbit reticulocyte lysate system) total RNAs. antibodies characterize two mutant strains deficient being devoid immunodetectable mRNA product. N-terminal amino acid sequence has been established frayed.