A comparative study of UTP-D-glucose-1-phosphate uridylyl transferase in the cysts of Echinococcus multilocularis and the livers of infected and control Meriones unguiculatus

Partial purification and comparison of the kinetic properties of ovine liver Echinococcus granulosus hydatid cyst fluid malate dehydrogenase and the cytoplasmic enzyme from the host liver

Ovine liver Echinococcus granulosus hydatid cyst fluid and cytoplasmic healthy ovine liver malate dehydrogenases were purified 24- and 30-fold by Sephadex G-200 and DEAE-Sephadex chromatography. Both enzymes were eluted with the same elution volume and the same salt concentration from the respective columns. The pH optimum of the enzymes from both sources was 8.4 in either Tris-HCl or barbital buffer. The Km values for oxaloacetate were 0.211 and 0.200 mM for hydatid cyst fluid and healthy ovine liver enzymes, respectively. The Km values for NADH were 0.220 and 0.213 mM for hydatid cyst fluid and healthy ovine liver enzymes, respectively. Enzyme from both sources demonstrated similar heat denaturation patterns. Both enzyme preparations were inhibited at high concentrations of either substrate. Neither enzyme was inhibited by para-hydroxymercuribenzoate or fumarate, and both enzyme preparations were specific for NADH as a cofactor. The results are discussed in terms of the possible infiltration of the host enzyme into the cyst fluid.

Synthesis of propargylic alcohols and biological effects on Echinococcus multilocularis metacestodes

This study describes the synthesis of propargylic alcohols derived from isatin and their biochemical and morphological effects on Echinococcus multilocularis metacestodes in Meriones unguiculatus. Propargylic alcohols decreased the alkaline phosphatase and the lactate dehydrogenase activities of the metacestode selectively. The most effective compound, 1b, decreased the lactate dehydrogenase enzymatic activity, and the glucose concentration in the parasite increased, whereas the glycogen content was partially decreased. Furthermore, the ultrastructure study revealed several damages. The host-parasite relationships are very important in the intrahepatic cestodes as shown by the biochemical side effects observed in the host's liver during the treatment. An in vitro enzymatic study was performed with alcohols 1b and 1c.

Inactivation of skeletal-muscle UDP-glucose pyrophosphorylase by reaction with carboxylate-directed reagents

Skeletal-muscle UDP-glucose pyrophosphorylase is inactivated by reaction with 2-ethoxy-N-(ethoxy-carbonyl)-1,2-dihydroquinoline (EEDQ) and 1-(3-dimethylaminopropyl-3-ethylcarbodi-imide (EDAC), two reagents specific for carboxylate groups. The former reagent is a more effective inactivator than EDAC. Although no evidence of reversible enzyme-reagent complexes of the affinity-labelling type was obtained by kinetic analysis of the inactivation, the selective protection of UDP-glucose pyrophosphorylase activity against inactivation by EEDQ in the presence of uridine substrates is indicative of an active-site-directed effect. The results are consistent with the hypothesis that EEDQ modifies a single carboxylate group located in a hydrophobic domain close to the substrate-binding site, leading to enzyme inactivation. In contrast, the reaction between UDP-glucose pyrophosphorylase and EDAC appears to involve a different region of the enzyme.

Echinococcus multilocularis: comparative study of glycogen synthase in metacestodes and in the livers of infected and control Meriones unguiculatus

A comparative study of the kinetic parameters of glycogen synthase was performed on Echinococcus multilocularis metacestodes and on the livers of infected and control host (Meriones unguiculatus). The enzyme of the parasite was found to be different from the enzyme of infected host liver. The apparent Km for UDP-glucose is 100 microM for the parasite and 400 microM for the host liver. The apparent Km for glucose 6-phosphate is 4 mM for the parasite and 2 mM for the host liver. The apparent Km for glycogen is 16 mg/ml for the parasite and 125 mg/ml for the host liver. The influence of glucose 6-phosphate and exogenous glycogen on the activity of glycogen synthase differs between the metacestode and the host liver. The enzyme of the metacestodes apparently does not need exogenous glycogen to work, contrary to the case for the liver host enzyme. The glycogen synthase of the parasite seems to be present in forms I and D, whereas the enzyme of the host liver appears in form I and that of the control liver in form D.