The presence of a proteolytic enzyme has been demonstrated in ground-up preparations of Schistosoma mansoni. A twenty-fold purification has been achieved by ultracentrifugation at pH 3.0; the enzyme has an optimum pH of 3.9 and a marked substrate specificity for haemoglobin. No significant proteolysis was observed either with whole serum at pH values of 3.9, 6.0 or 8.0, or with isolated serum proteins at pH ranges between 2.5 and 7.7. The evidence is discussed that this enzyme may be located in the intestine of the schistosomes and that it is, at least in part, responsible for the supply of amino acids to the organisms.

Animals↗

PubMed1959

The effect of piperazine on succinate production by Ascaris lumbricoides.

Piperazine reduced the production of succinate by Ascaris lumbricoides. This effect was reversible. There was a close parallelism between the concentrations of piperazine which paralysed the worm and those which inhibited the formation of succinate. Piperazine did not affect the incorporation of [2-(14)C]lactate into succinate by strips of Ascaris muscle. It was concluded that production of succinate supplies energy for the contraction of Ascaris muscle.

Animals↗

PubMed1959

Mechanisms of action of schistosomicidal agents.

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Anthelmintics↗

PubMed1957

The relationship between inhibition of phosphofructokinase activity and the mode of action of trivalent organic antimonials on Schistosoma mansoni.

The addition of purified mammalian phosphofructokinase to homogenates of schistosoma mansoni increased the rate of lactic acid production from glucose and reversed the inhibition of glycolysis produced by low concentrations of trivalent organic antimonials. Neither mammalian phosphofructokinase nor trivalent antimonials affected the rate of lactic acid production from fructose-1:6-diphosphate (HDP) by schistosome homogenates. Accordingly, in the schistosome, the rate of glycolysis of glucose is determined by the activity of phosphofructokinase.The aldolase of S. mansoni has a high requirement for HDP; relatively slight reductions in the concentration of this substrate below the optimum resulted in a sharp decline of aldolase activity. Therefore, decreased formation of HDP, due to inhibition of schistosome phosphofructokinase activity by antimonials, reduced the activity of aldolase and resulted in an inhibition of glycolysis of schistosome homogenates.Kinetic data revealed differences in the nature of the phosphofructokinase of S. mansoni and that of the enzyme catalysing the same reaction in the host. Exposure of schistosomes to low concentrations of potassium antimonyl tartrate or administration of subcurative doses of stibophen to the host resulted in an accumulation of the substrate (fructose-6-phosphate), and a reduction of the product (HDP) of the phosphofructokinase reaction, indicating that the activity of this enzyme was inhibited by antimonials in the intact parasite. It is concluded that inhibition of phosphofructokinase activity can account for the mechanism of the chemotherapeutic action of trivalent organic antimonials in schistosomiasis.

Animals↗

PubMed1957