Haemoproteus and Schistosoma synthesize heme polymers similar to Plasmodium hemozoin and beta-hematin

Many parasites digest hemoglobin as an amino acid source, but only a few pr oduce heme polymer pigment instead of catabolizing heme via heme oxygenase. This work compares purified heme polymers produced by Haemoproteus columba e and Schistosoma mansoni to that of Plasmodium falciparum hemozoin and syn thetic beta -hematin. Fourier-transform infrared spectroscopy identifies th e signature peaks of the common iron-carboxylate bond characteristic in all four heme polymers. However, all pigments could be distinguished by quite different three-dimensional structure visualized by Field Emission Inlens S canning Electron Microscopy. Both P. falciparum and H. columbae heme polyme rs had a symmetrical shape unlike the amorphous S. mansoni heme polymer and beta -hematin. All four heme pigments serve as templates for heme polymer extension, which was inhibitable by chloroquine and other quinoline antimal arials. The polymers showed different levels of resistance to hydrogen pero xide degradation. This work identifies another genus, Haemoproteus, capable of intracellular heme polymer formation. The different three-dimensional s tructures of each pigment implicate genus specific formation of heme polyme r, variation of inhibition of polymer extension by the quinolines and degra dation by hydrogen peroxide. (C) 2001 Elsevier Science B.V. All rights rese rved.