Pyruvate kinases and carbon dioxide fixating enzymes in the digestive gland of Littorina saxatilis rudis (Maton) and in the daughter sporocysts of Microphallus Similis (Jäg.) (Digenea: Microphallidae)

Abstract

1.1. Pyruvate kinases from the daughter sporocysts of Microphallus similis and from the digestive gland of Littorina saxatilis rudis show simple hyperbolic, substrate kinetics, an optimum pH of 7·2, strong activation by FDP and inhibition by ATP and alanine. The inhibition by ATP and alanine is counteracted by FDP. The enzyme from the parasite has less specific cofactor requirements than the enzyme from the host.2.2. The carbon dioxide fixating enzymes, phosphoenolpyruvate carboxykinase and malic enzyme are present, maximum activity of the former occurring at pH 7·3 with IDP and Mn2+ the most effective cofactors.3.3. The major role of malic enzyme in the mollusc and parasite is probably decarboxylation of malate to produce pyruvate.