Hemozoin nucleation

Another possible participant in hemozoin nucleation is the histidine-rich protein (HRP). Using monoclonal antibodies to probe the proteins of the digestive food vacuole of P. falciparum, Sullivan et al. identified two histidine-rich proteins, HRP II and HRP III, and demonstrated that these proteins could mediate the formation of hemozoin [37]. HRP II (Mr 35 kD) contains 51 repeats of the sequence Ala-His-His (76% of the mature protein is histidine and alanine) [38], while HRP III (Mr 27 kD) contains 28 Ala-His-His sequences (56% of the mature protein is histidine and alanine) [39]. While a clone lacking both HRP II and III has been shown to produce hemozoin, a third protein which cross reacted with anti-HRP monoclonal antibodies has also been found in the digestive vacuole of this strain. Although this protein has not been isolated or shown to mediate hemozoin formation, a candidate is HRP IV (Mr 10 kD) which is 31% histidine [40]. 

Inhibition of the nucleation and/or growth of the hemozoin crystals induced by FQ may be explained by the stereoselective binding of FQ with faces thereof. Generally, the two forms, biogenic (hemozoin) and synthetic (P-hematin), of the malaria pigment present three dominant crystal feces [h k 1 of the [100] side surfaces, 010 face that is perpendicular to each other, and the 011 fece that is inclined relative to the c-axis, ending at each end of crystal [85]. Sometimes, the biogenic hemozoin crystals have a face 001, which is perpendicular to the c-axis and that does not develop properly. The 001 face is exposed to the... 

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