Abstract
The present investigation indicates the presence of thymidine phosphorylase (TPase) (EC.2.4.2.4) and its activity in supernatant fraction of Echinococcus granulosus protoscoleces extract, furthermore some of its kinetics properties were investigated. It was found that deoxyuridine might be an alternative substrate for thymidine during catalyzed reaction by enzyme TPase. The result also indicated that TPase activity was extremely sensitive to inhibite by thymine(product reaction), cytidine, 5-flourouracil and albendazole with inhibitory percentages of: 36%, 68%, 52% and 3% respectively. The presence of TPase activity indicates the presence of salvage pathway for thymine nucleotide which was essential to deoxyribonucleic acid (DNA) synthesis in this organism, in addition to de novo pathway.
Highlights
Echinococcus granulosus belongs to the phylum: Platyhelminthes, class: Cestoda, Order: Cyclophyllidea, family: taeniidae (Roberts and Jenovy,1996)
The result showed that the 45000xg supernatant fraction was the cellular fraction of choice, in which protoscoleces Thymidine phosphorylase (TPase) activity was found
The results showed that cytidine had the highest inhibitory effect on TPase activity (68%), 5-fluorouracil (52%), thymine (36%) and the lowest inhibitory effect was for albendazole (3%)
Summary
Echinococcus granulosus belongs to the phylum: Platyhelminthes, class: Cestoda, Order: Cyclophyllidea, family: taeniidae (Roberts and Jenovy,1996). E.granulosus is widely distributed throughout temperate and subtropical regions. Human infection is common in southern south America, much of Africa, Eastern and southern Europe, the Middle East, southern Australia, New Ziland and extensive areas of Asia, including Iraq (Andersen et al.,1997). It has become increasingly apparent that understanding parasite biomolecular metabolism and the present differences and similarities in mammalian hosts is very important. It is the target from which researchers may put treatment strategies for parasitic diseases, for instance the formation of thymine nucleotide is an important step in the complex of metabolic events, which supply nucleotide building blocks for DNA replication (Hassan and Coombs,1988). The TPase catalyzes reaction in both eukaryotic and prokaryotic, thymidine is synthesized from thymine and deoxyribose-1-phosphate in a reaction catalyzed by TPase (Shaw et al, 1988)
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