Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P01189 (beta-endorphin)
 21,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An ATP diphosphohydrolase was identified in the plasma membranes isolated from promastigote forms of Leishmania amazonensis. Both ATP and ADP were hydrolysed at similar rates by the enzyme. Other nucleotides such as UTP, GTP and CTP were also degraded, revealing a broad substrate specificity. Adding ATP and ADP simultaneously, the amount of hydrolysis achieved was compatible with the presence of a single enzyme. ATPase activity was not affected by addition of vanadate, ouabain, thapsigargin, dicyclohexylcarbodiimide, oligomycin and bafilomycin A, thus excluding involvement of P-, F- and V-type ATPases. The effects of pH in the range 6.5-8.5 were examined using ATP or p-NPP as substrate. At pH 7.4, the phosphatase activity decreased, and did not show a significant contribution to ATP hydrolysis. In addition, the enzyme was not inhibited by levamisole and ammonium molybdate, excluding alkaline phosphatase and nucleotidase activities, respectively. Sodium azide (5-10 mM) caused inhibition of the ATP and ADP hydrolysis in a dose-dependent manner. Calcium was the best activating metal ion for both ATPase and ADPase activities. Ultrastructural cytochemical microscopy showed ATP diphosphohydrolase on the surface and flagellar pocket of the parasite. We have proposed that L. amazonensis ATP diphosphohydrolase may participate in the salvage pathway of nucleosides.
 ...
PMID:Characterization and cytochemical localization of an ATP diphosphohydrolase from Leishmania amazonensis promastigotes. 1186 92

In the present study we investigate the biochemical properties of the members of NPP family in synaptosomes prepared from rat heart left ventricles. Using p-nitrophenyl-5'-thymidine monophosphate (p-Nph-5'-TMP) as substrate for E-NPPs in rat cardiac synaptosomes, we observed an alkaline pH dependence, divalent cation dependence and the K ( M ) value corresponded to 91.42 +/- 13.97 microM and the maximal velocity (V ( max )) value calculated was 63.79 +/- 3.59 nmol p-nitrophenol released/min/mg of protein (mean +/- SD, n = 4). Levamisole (1 mM), was ineffective as inhibitor of p-Nph-5'-TMP hydrolysis in pH 8.9 (optimum pH for the enzyme characterized). Suramin (0.25 mM) strongly reduced the hydrolysis of p-Nph-5'-TMP by about 46%. Sodium azide (10 and 20 mM) and gadolinium chloride (0.3 and 0.5 mM), E-NTPases inhibitors, had no effects on p-Nph-5'-TMP hydrolysis. RT-PCR analysis of left ventricle demonstrated the expression of NPP2 and NPP3 enzymes, but excluded the presence of NPP1 member. By quantitative real-time PCR we identified the NPP3 as the enzyme with the highest expression in rat left ventricle. The demonstration of the presence of the E-NPP family in cardiac system, suggest that these enzymes could contribute with the fine-tuning control of the nucleotide levels at the nerve terminal endings of left ventricles that are involved in several cardiac pathologies.
 ...
PMID:Biochemical characterization of ecto-nucleotide pyrophosphatase/phosphodiesterase (E-NPP, E.C. 3.1.4.1) from rat heart left ventricle. 1778 43