Carbon dioxide fixation in malaria—I. Kinetic studies in plasmodium lophurae

Absence of α‐Ketoglutarate Dehydrogenase Activity and Presence of CO2‐Fixing Activity in Plasmodium falciparum Grown In Vitro in Human Erythrocytes1

“…It is, however, difficult to compare our results with those obtained with duck or monkey malaria parasites, as in those experiments only trace levels of bicarbonate were employed and specific activities cannot therefore be computed. When trace levels of bicarbonate were used in cultures infected with P. falciparum, however, much less I4CO, fixation was observed in terms of dpm, even allowing for the lower hematocrit used in the present studies as compared to the earlier studies on P. bphurae (15) and P. knowlesi (1 2). Perhaps some of this difference can be attributed to the absence of white cells in the present studies, which used cultured erythrocytes rather than fresh blood.…”

“…Metabolism of /I-'4CJglutamate. Culture flasks (Nunc) containing approximately 15 tained as uninfected controls. When over 15% of the erythrocytes contained trophozoites, as revealed by Giemsa staining, both the control and parasitized cultures were centrifuged, the supernatants discarded, and the cells washed once in phosphatebuffered saline (PBS) and resuspended in PBS at about 6 x 1 O8 cells/ml (Analys Instrument Cell Counter, Stockholm, Sweden).…”

Hemoglobin degradation in the human malaria pathogen Plasmodium falciparum: a catabolic pathway initiated by a specific aspartic protease.

“…The organism avidly ingests host hemoglobin and degrades it in a specialized proteolytic organelle called the digestive vacuole (1)(2)(3)(4). As the parasite has a limited capability for de novo synthesis (5,6) or exogenous uptake (7) of amino acids, the hemoglobin is catabolized to provide amino acids for growth and maturation (6,8,9). The process of hemoglobin breakdown releases heme, which is detoxified by polymerization into a crystalline pigment, hemozoin (10,11) .…”

Purine Uptake and Utilization by the Avian Malaria Parasite Plasmodium lophurae*

“…The present work was undertaken to study the uptake and utilization of preformed purines by P. lophurae P. lophurae was maintained in Whitc Pekin ducklings (3)(4)(5)(6) weeks old) by weekly transfer of infected blood as previously described (25,26). Blood was withdrawn from the jugular vein into syringes containing 1 ml of heparin solution (30 mg/ 100 ml of 0.15 M NaC1) for each 9 ml of blood to be taken.…”