Mechanism of malarial haem detoxification inhibition by chloroquine

Pandey, Amit V.; Bisht, Himani; Babbarwal, Vinod K.; Srivastava, Jaya; Pandey, Kailash C.; Chauhan, Virander S. (2001). Mechanism of malarial haem detoxification inhibition by chloroquine. Biochemical journal, 355(Pt 2), pp. 333-338. Portland Press 10.1042/bj3550333

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The haem detoxification pathway of the malaria parasite Plasmodium falciparum is a potential biochemical target for drug development. Free haem, released after haemoglobin degradation, is polymerized by the parasite to form haemozoin pigment. Plasmodium falciparum histidine-rich protein-2 (Pfhrp-2) has been implicated as the catalytic scaffold for detoxification of haem in the malaria parasite. Previously we have shown that a hexapeptide repeat sequence (Ala-His-His-Ala-Ala-Asp), which appears 33 times in Pfhrp-2, may be the major haem binding site in this protein. The haem binding studies carried out by ourselves indicate that up to 18 equivalents of haem could be bound by this protein with an observed K(d) of 0.94 microM. Absorbance spectroscopy provides evidence that chloroquine is capable of extracting haem bound to Pfhrp-2. This was supported by the K(d) value, of 37 nM, observed for the haem-chloroquine complex. The native PAGE studies reveal that the formation of the haem-Pfhrp-2 complex is disrupted by chloroquine. These results indicate that chloroquine may be acting by inhibiting haem detoxification/binding to Pfhrp-2. Moreover, the higher affinity of chloroquine for haem than Pfhrp-2 suggests a possible mechanism of action for chloroquine; it may remove the haem bound to Pfhrp-2 and form a complex that is toxic to the parasite.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Pre-clinic Human Medicine > BioMedical Research (DBMR) > DCR Unit Tiefenau Hospital (discontinued) > Forschungsgruppe Endokrinologie/Diabetologie/Metabolik (Pädiatrie) (discontinued)

UniBE Contributor:

Pandey, Amit Vikram

Subjects:

500 Science > 570 Life sciences; biology

ISSN:

0264-6021

Publisher:

Portland Press

Language:

English

Submitter:

Amit Vikram Pandey

Date Deposited:

25 Aug 2014 14:52

Last Modified:

21 Sep 2016 09:21

Publisher DOI:

10.1042/bj3550333

PubMed ID:

11284719

Uncontrolled Keywords:

Histidine-rich protein, Plasmodium, Malaria, Haemoglobin, Haemozoin

BORIS DOI:

10.7892/boris.41750

URI:

https://boris.unibe.ch/id/eprint/41750

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