Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.3.5 (5'-nucleotidase)
 3,167 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

WI-L2 cells (a B-lymphoblastoid cell line) were more resistant than CEM cells (a T-lymphoblastoid cell line) to deoxyadenosine, ara-A (9-beta-D-arabinofuranosyladenine), or ara-C (1-beta-D-arabinofuranosylcytosine) inhibition. This was caused by a difference in the composition of cytosol 5'-nucleotidases between WI-L2 and CEM cells. In intact cells, the endogenous production of deoxyadenosine from WI-L2 cells deficient in adenosine kinase (EC 2.7.1.20) and deoxycytidine kinase (EC 2.7.1.74) was consistently high, despite changes in endogenous adenosine production. Endogenous production of deoxyadenosine from CEM cells deficient in adenosine kinase and deoxycytidine kinase was, however, coordinated with endogenous adenosine production. In broken cells, cytosol dAMPase (2'-deoxyadenosine 5'-monophosphate 5'-nucleotidase) activity of WI-L2 cells was 3-5-fold higher than that of CEM cells. dAMPase activity could be separated from ATP-activated IMPase (inosine 5'-monophosphate 5'-nucleotidase) by gel filtration (molecular weight: dAMPase; 39,000-46,000; ATP-activated IMPase, greater than 150,000). Cytosol ATP-activated IMPase and dAMPase were isolated by phosphocellulose or DEAE-Bio-Gel A chromatography from non-specific phosphatases. The ATP-activated IMPase showed only marginal activity towards dAMP (2'-deoxyadenosine 5'-monophosphate), ara-AMP (9-beta-D-arabinofuranosyladenine 5'-monophosphate), or ara-CMP (cytosine-beta-D-arabinofuranoside 5'-monophosphate), even in the presence of ATP. The activity of ATP-activated IMPase was similar in WI-L2 and CEM cells. dAMPase was separated into two peaks by DEAE-Bio-Gel A chromatography; one of these peaks degraded ara-AMP and ara-CMP. The activities of both peaks from WI-L2 cells were higher than those from CEM cells. These results show that the degradation of dAMP, ara-AMP or ara-CMP was more specific and rapid in WI-L2 than in CEM cells.
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PMID:Differential composition of cytosol 5'-nucleotidases between T and B lymphoblasts. 301 Nov 14

Intracellular accumulation of triphosphorylated derivatives is essential for the cytotoxic activity of nucleoside analogues. Different mechanisms opposing this accumulation have been described. We have investigated the dephosphorylation of monophosphorylated fludarabine (F-ara-AMP) by the purified cytoplasmic 5'-nucleotidase cN-II using HPLC and NMR. These studies clearly showed that cN-II was able to convert F-ara-AMP into its non phosphorylated form, F-ara-A, with a Km in the millimolar range and Vmax = 35 nmol/min/mg, with both methods. Cytoplasmic 5'-nucleotidase cN-II can degrade this clinically useful cytotoxic nucleoside analogue and its overexpression is thus likely to be involved in resistance to this compound.
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PMID:F-ara-AMP is a substrate of cytoplasmic 5'-nucleotidase II (cN-II): HPLC and NMR studies of enzymatic dephosphorylation. 1662 21