Biochemical characterization of Plasmodium falciparum hemozoin
Goldie, P.; Roth, E.F.; Oppenheim, J.; Vanderberg, J.P.
American Journal of Tropical Medicine and Hygiene 43(6): 584-596
1990
ISSN/ISBN: 0002-9637 PMID: 2267961 Document Number: 367336
Haemozoin was prepared from Plasmodium falciparum-infected erythrocytes by hypotonic lysis, repeated sonication and sucrose gradient sedimentation. The resultant material was found to be composed of 65% protein, 16% ferriprotoporphyrin-IX, 6% carbohydrate and trace amounts of lipid and nucleic acids. The overwhelming majority of the protein component was derived from a mixture of native and denatured human globin non-covalently associated with the metalloporphyrin. These observations conflict with those of J.O. Ashong, I.P. Blench and D.C. Warhurst [see Trop. Dis. Bull., 1990, 87, abst. 158] who found a higher percentage (41-45%) of ferriprotoporphyrin-IX present, and that the protein component was parasite-derived and unlike haemoglobin in amino-acid composition.[The explanation for these differences may possibly be found in the differing techniques of preparation, and control of the purity of the haemozoin in the 2 studies. In the study of Ashong et al., parasites free from erythrocyte material were used for the preparation of haemozoin, and the purity of the preparations was monitored by electron microscopic examination. Extensive contamination of the preparation with globin in the present study may be accounted for by sonication in the presence of haemoglobin.Both these studies should be examined in the light of the recent report of Slater et al. (Proceedings of National Academy of Sciences of the United States of America, 1991, 88, 325-329) where X-ray diffraction and infra-red spectrum evidence is presented that haemozoin may be a simple polymer of ferriprotoporphyrin-IX residues linked by iron-carboxylate bonds as in "B-haematin". The haemozoin in that study was prepared by a careful technique which, although it included proteolytic digestion, did not alter the spectral or solubility characteristics of the material. Iron porphyrins are known to bind protein avidly, and Slater et al. conclude that the protein material often observed associated with purified "haemozoin" is not an essential component of the material. The nature of the associated protein may perhaps simply reflect the conditions under which the haemozoin was prepared.]D.C. Warhurst Haemozoin of P. falciparum was found to be composed of 65% protein, 16% ferriprotoporphyrin-IX (haematin), 6% carbohydrate, and trace amounts of lipid and nucleic acids. The overwhelming majority of the protein component is a mixture of native and denatured human globin non-covalently associated with the metalloporphyrin. Immunoelectron microscopy, employing anti-human haemoglobin as a probe, identified in situ association of haemoglobin with haemozoin. Haemozoin produced within diabetic blood had a higher proportion of carbohydrate, suggesting that the carbohydrate component comes from non-enzymatic glycosylation of haemoglobin.