Uptake of iron from hemoglobin and the haptoglobin-hemoglobin complex by hemolytic bacteria

The abilities of Staphylococcus aureus and Streptococcus pyogenes to remove iron from mouse 59Fe hemoglobin that was either in free form or complexed with human haptoglobin, were evaluated. 59Fe hemoglobin from the amphibian Taricha granulosa was also used in free form or complexed with the amphibian's hemoglobin-binding proteins. Contrary to what was reported from a study using pathogenic Escherichia coli, haptoglobin failed to exhibit a bacteriostatic influence when complexed with hemoglobin. In our study, more 59Fe was removed by the bacteria from the haptoglobin-hemoglobin complex than from free mouse hemoglobin. The hemoglobin and hemoglobin-plasma protein complexes of Taricha were stripped of 59Fe at similar rates and extents by both bacterial species.