Studies on phytoferritin: I. Identification and localization

A new iron-protein complex, phytoferritin, has been identified microscopically, centrifugally, and spectrophotometrically in extracts from pea embryos. Methods for extracting 90% pure phytoferritin from pea embryonic axes, cotyledons, and young bean leaves have been developed. They include differential centrifugation and DEAE-cellulose column chromatography. The electron microscopic image, ultraviolet absorption spectrum, iron:protein ratio, and sedimentation behavior of phytoferritin closely resemble those of animal ferritin. Phytoferritin has been located electron microscopically in the proplastids of pea epicotyls and root meristems and in plastids of young light- or dark-grown bean seedlings. In addition masses of phytoferritin have been identified in the plastids of the peripheral layers of pea cotyledons.