Expression of human malaria parasite purine nucleoside phosphorylase in host enzyme-deficient erythrocyte culture. Enzyme characterization and identification of novel inhibitors.

Published

Journal Article

The intraerythrocytic human malaria parasite, Plasmodium falciparum, requires a source of hypoxanthine for nucleic acid synthesis and energy metabolism. Adenosine has been implicated as a major source for intraerythrocytic hypoxanthine production via deamination and phosphorolysis, utilizing adenosine deaminase and purine nucleoside phosphorylase, respectively. To study the expression and characteristics of human malaria purine nucleoside phosphorylase, P. falciparum was successfully cultured in purine nucleoside phosphorylase-deficient human erythrocytes to an 8% parasitemia level. Purine nucleoside phosphorylase activity was undetectable in the uninfected enzyme-deficient host red cells but after parasite infection rose to 1.5% of normal erythrocyte levels. The parasite purine nucleoside phosphorylase was not cross-reactive with antibody against human enzyme, exhibited a calculated native molecular weight of 147,000, and showed a single major electrophoretic form of pI 5.4 and substrate specificity for inosine, guanosine and deoxyguanosine but not xanthosine or adenosine. The Km values for substrates, inosine and guanosine, were 4-fold lower than that for the human erythrocyte enzyme. In these studies we have identified two novel potent inhibitors of both human erythrocyte and parasite purine nucleoside phosphorylase, 8-amino-5'-deoxy-5'-chloroguanosine and 8-amino-9-benzylguanine. These enzyme inhibitors may have some antimalarial potential by limiting hypoxanthine production in the parasite-infected erythrocyte.

Full Text

Duke Authors

Cited Authors

  • Daddona, PE; Wiesmann, WP; Milhouse, W; Chern, JW; Townsend, LB; Hershfield, MS; Webster, HK

Published Date

  • September 1986

Published In

Volume / Issue

  • 261 / 25

Start / End Page

  • 11667 - 11673

PubMed ID

  • 3091593

Pubmed Central ID

  • 3091593

Electronic International Standard Serial Number (EISSN)

  • 1083-351X

International Standard Serial Number (ISSN)

  • 0021-9258

Language

  • eng