Partial purification and properties of ovine liver Echinococcus granulosus protoscolices phospholgucose isomerase

Echinococcus granulosus protoscolex is the actual larval stage of the cestode causing echinococcosis both in man and animals. In the present report, certain properties of phosphoglucose isomerase from the ovine liver E. granulosus protoscolices have been studied and compared with those of the hydatid cyst fluid and the healthy ovine liver enzymes. The protoscolices enzyme prepared in a manner similar to the hydatid cyst fluid and the ovine liver enzymes exhibited the following properties: (1) pH optimum of 8.2 (2) KM value of 0.23 mM, (3) the enzyme was inhibited in the presence of high concentrations of alpha-D-glucose 6-phosphate, (4) no detectable inhibition of the enzyme was observed in the presence of phosphate ion up to 4.1 mM, (5) the protoscolices enzyme was less thermostable as compared to the hydatid cyst fluid and the ovine liver enzymes, (6) the protoscolices enzyme had a lower Ki value (0.7 mM) as compared to either the hydatid cyst fluid (1.1 mM) or the ovine liver enzymes (4.6 mM) when 6-phosphogluconic acid was used as a competitive inhibitor.