Microsc. Microanal. Microstruct. 6, 33-40 (1995)
DOI: 10.1051/mmm:1995105

Electron Energy Loss Spectroscopy Study of Iron Deposition in Human Alveolar Macrophages: Ferritin or Hemosiderin?

Marco Diociaiuti, Mario Falchi et Luigi Paoletti

Laboratorio di Ultrastrutture, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Roma, Italy

Abstract
Electron energy loss spectroscopy imaging (EELSI) was used to obtain Fe maps, with molecular resolution, in human alveolar macrophages. Fe concentrations were found in particular structures named siderosomes. The combined application of Extended energy loss fine structure (EXELFS) analysis, a "short-range" probe, and Selected area electron diffraction (SAED), a "long-range" probe, allowed us to investigate the atomic arrangement of proteins constituting the siderosomes. Results are compared with structural data obtained on purified proteins. It is found that the siderosomes seem to be constituted mainly by normal hemosiderins.

PACS
8715 - Biomolecules: structure and physical properties.
8764L - Electron and photoelectron spectroscopy.
8764D - Scanning tunneling and atomic force microscopy.

Key words
Iron -- Uptake -- Ferritin -- Macrophage -- Method -- Molecular arrangement -- Pulmonary alveolus -- Human -- Lysosome -- Vertebrates physiology -- Respiratory system -- Biological sciences -- Life sciences -- Ferroprotein -- Lung


© EDP Sciences 1995