title: Pathways of pyrimidine nucleotide biosynthesis in gravid Angiostrongylus cantonensis.
abstract: The incorporation of radioactive precursors into pyrimidine nucleotides via de novo and salvage pathways was measured in gravid Angiostrongylus cantonensis by HPLC and thin-layer chromatography. 14C-labelled orotate, uridine, uracil and deoxyuridine were traced to UMP, UDP, UTP, UDP-glucose, dTMP, CMP, CDP and CTP. 3H-labelled cytidine was also incorporated into both uracil and cytosine nucleotides in a ratio of 2:1. Cytosine was a major end-product for all the precursors. Cytosine nucleotides were probably formed from UTP by the action of CTP synthetase whose activity in crude cell-free extract was 31.5 +/- 4.9 pmol min-1 (mg protein)-1. It was dependent on glutamine, ATP and GTP and was inhibited by CTP. The total amount of pyrimidine nucleotides formed from uridine was 3 times of that from uracil. The presence of uracil in the metabolism of uridine indicates that UMP is formed by uracil phosphoribosyltransferase as well as by uridine kinase. UMP is a key intermediate for cytidylate and thymidylate biosynthesis in the gravid worms.
authors.affiliation: Department of Biochemistry, University of Hong Kong.
authors.forename: N N
authors.initials: NN
authors.lastname: So
authors.forename: P C
authors.initials: PC
authors.lastname: Wong
authors.forename: R C
authors.initials: RC
authors.lastname: Ko
mesh_terms: D017185:Angiostrongylus cantonensis / Q000378:metabolism*; D000818:Animals; D019731:Carbon-Nitrogen Ligases; D003562:Cytidine / Q000378:metabolism; D003857:Deoxyuridine / Q000378:metabolism; D005260:Female; D008025:Ligases / Q000378:metabolism; D011742:Pyrimidine Nucleotides / Q000096:biosynthesis*; D011743:Pyrimidines / Q000378:metabolism; D014498:Uracil / Q000378:metabolism; D014529:Uridine / Q000378:metabolism
chemical_list: D011742:Pyrimidine Nucleotides; D011743:Pyrimidines; D014498:Uracil; D003562:Cytidine; D008025:Ligases; D019731:Carbon-Nitrogen Ligases; C019951:CTP synthetase; D003857:Deoxyuridine; D014529:Uridine