Lysosomal and cytosolic ferritins. A biochemical and electron-spectroscopic study

• Published in: Biology of metals 1989, Vol.2 (2), p.114-121
• Main Authors: Ringeling, P L, Cleton, M I, Kroos, M J, Sorber, L W, de Bruyn, W C, Harrison, P M, van Eijk, H G
• Format: Article
• Language: English
• Subjects: Animals; Chromatography, Gel; Cytosol - analysis; Electron Probe Microanalysis; Ferritins - isolation & purification; Hemosiderin - isolation & purification; Iron - analysis; Liver - analysis; Lysosomes - analysis; Male; Microscopy, Electron; Phosphorus - analysis; Rats; Rats, Inbred Strains
• ISSN: 0933-5854; 1572-8773
• DOI: 10.1007/BF01129210

Cytosolic and lysosomal ferritin and haemosiderin were isolated from rat livers which had been iron-loaded by four intraperitoneal injections of iron-dextran. The cytosolic and lysosomal ferritins, prepared in a phosphate-free medium, were subjected to gel-filtration chromatography on Sepharose 6B, yielding four fractions: a cytosolic monomeric (CMF) and void-volume ferritin fraction (CVVF), and a lysosomal monomeric (LMF) and void-volume ferritin fraction (LVVF). Of each fraction the following aspects were examined: (a) immunoreactivity against specific antiserum; (b) the Fe/P mass ratio and the effect of dialysis on this ratio using electron probe micro-analysis (EPMA); (c) morphology and Fe-specific imaging using electron spectroscopic imaging (ESI) and electron energy loss spectroscopy (EELS). For haemosiderin one aspect, the Fe/P ratio, was determined before and after extensive purification. The following results were obtained (a) All ferritin fractions reacted with anti- (rat liver ferritin). (b) The Fe/P ratios as determined in CMF in an haemosiderin were not affected by dialysis or extensive purification, respectively. The Fe/P ratio in CVVF was affected by dialysis. In the lysosomal fractions, only a trace of phosphorus (LVVF) or no phosphorus (LMF) was detected. (c) Morphologically, CMF and CVVF were found to be rather homogeneous; the iron core diameters of both fractions were in the known size range.