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Malic Dehydrogenase Heterogeneity in Malaria (Plasmodium lophurae and P. berghei) *
Author(s) -
SHERMAN IRWIN W.
Publication year - 1966
Publication title -
the journal of protozoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.067
H-Index - 77
eISSN - 1550-7408
pISSN - 0022-3921
DOI - 10.1111/j.1550-7408.1966.tb01918.x
Subject(s) - malate dehydrogenase , enzyme , biochemistry , biology , malic enzyme , citrate synthase , red cell , lactate dehydrogenase , plasmodium berghei , microbiology and biotechnology , electrophoresis , red blood cell , dehydrogenase , malaria , computer security , computer science , immunology
SYNOPSIS. Molecular heterogeneity of malic dehydrogenase (MDH) in malaria was shown by zone electrophoresis in potato starch, starch gel, and by enzymatic activity with analogs of the coenzyme diphosphopyridine nucletide. A single anodal peak of MDH characterized the normal duck red blood cell whereas P. lophurae free of the host cell had a cathodal form of the enzyme. Infected duck erythrocytes had a combination of these electrophoretic forms. The isolated enzymes had different pH optima with oxaloacetate as substrate: pH 7.4 for the duck red cell and 6.4 for the plasmodial enzyme. The Km of each enzyme for oxaloacetate varied with the pH. The Km at pH 7.4 was 4.1 and 4.4 × 10 5 M for parasite and host, respectively, whereas at 6.4 it was 2.0 × 10 5 M for P. lophurae and 6.3 × 10 5 M for the duck erythrocyte. At pH 7.4 both enzymes were inhibited by oxaloacetate concentrations greater than 10 −4 M. P. berghei MDH also had a different electrophoretic character from that of the mouse red blood cell. Quantitatively, MDH activity increased with parasitization, and erythrocyte‐free P. lophurae contained approximately twice the activity found in the uninfected duck erythrocyte. The quantity of MDH activity of the infected cell was ca. 50% less than the sum of the activities of the parasite and the uninfected cell. It is suggested that these properties of the parasite MDH may give it a physiologic advantage over the red cell under the conditions which prevail intraerythrocytically.