| Summary: | Theories of the structure of the protein component of the iron-storage molecule ferritin include the simple model of 24 identical subunits of molecular weight about 18500 and several more complex but less well defined models which require the presence of other subunits (with a wide range of molecular weights) as well as the original one. The various hypotheses are mutually irreconcilable and are based on the characterization of "subunits" by different techniques for separation and analysis. In an attempt to resolve this problem, a comparative study has been carried out on the quaternary structure of ferritin purified from horse spleen, human spleen and rat liver. Isolated, purified ferritin preparations were dissociated by a range of reagents - acetic acid, guanidine hydrochloride and sodium dodecyl sulphate - and the products were separated by gel filtration and polyacrylamide gel electrophoresis. The products obtained in each case were subjected as far as possible to analysis by alternative methods in order to bridge the experimental gaps between the various laboratories concerned. In the event, the experimental findings of other laboratories have been substantially confirmed, even where alternative methods of characterization have been used. It can only be concluded that at least some of the original data have been too simplistically interpreted, and resolution of the controversy must await new experimental work.
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