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)

The organelle pathology of neutrophils in chronic granulocytic leukaemia (CGL) was investigated by analytical subcellular fractionation. There were minor reductions in activity of some granule enzymes with an abnormal distribution in sucrose density gradients of the specific granules. There was a marked reduction of 5'-nucleotidase activity but this is probably related to the relative reduction of the mononuclear cell contamination of the neutrophils isolated from leukaemic patients compared with controls. Another plasma membrane enzyme, NADH-nitroblue tetrazolium reductase, which has a microbicidal role, had increased activity. Neutrophils from patients with CGL had 13% the alkaline phosphatase activity of controls and were compared with neutrophils from women in the third trimester of pregnancy when the activity was increased to 8 times the control level. The latent activity, per cent inhibition by Levamisole, kinetic constants and subcellular distribution of alkaline phosphatase were similar in the three groups. It is suggested that the properties and intracellular localization of alkaline phosphatase are normal in CGL and that there is a quantitative lack of enzyme.
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PMID:Studies on the subcellular organelles of neutrophils in chronic granulocytic leukaemia with special reference to alkaline phosphatase. 28 20

Adenosine, a well-known neuromodulator, may be formed intracellularly in the CNS from degradation of AMP and then exit via bi-directional nucleoside transporters, or extracellularly by the metabolism of released nucleotides. This study reports the enzymatic properties of an ecto-5'-nucleotidase activity in brain membranes of zebrafish (Danio rerio). This enzyme was cation-dependent, with a maximal rate for AMP hydrolysis in a pH range of 7.0-7.5 in the presence of Mg(2+). The enzyme presented a maximal activity for AMP hydrolysis at 37 degrees C. The apparent K(m) and V(max) values for Mg(2+)-AMP were 135.3+/-16 microM and 29+/-4.2 nmol Pi.min(-1).mg(-1) protein, respectively. The enzyme was able to hydrolyze both purine and pyrimidine monophosphate nucleotides, such as UMP, GMP and CMP. Levamisole and tetramisole (1 mM), specific inhibitors of alkaline phosphatases, did not alter the enzymatic activity. However, a significant inhibition of AMP hydrolysis (42%) was observed in the presence of 100 microM alpha,beta-methylene-ADP, a known inhibitor of ecto-5'-nucleotidase. Since 5'-nucleotidase represents the major enzyme responsible for the formation of extracellular adenosine, the enzymatic characterization is important to understand its role in purinergic systems and the involvement of adenosine in the regulation of neurotransmitter release.
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PMID:Ecto-5'-nucleotidase activity in brain membranes of zebrafish (Danio rerio). 1546 66

CD73 metabolizes extracellular 5'-AMP to adenosine; yet recent experiments in brain tissue suggest that CD73 is not required for the metabolism of 5'-AMP to adenosine because of tissue nonspecific alkaline phosphatase (TNAP), which like CD73 is a GPI-anchored ecto-enyzme with 5'-nucleotidase activity. Because adenosine importantly regulates renovascular function, we investigated whether both TNAP and CD73 are involved in the renovascular metabolism of 5'-AMP. To test this, we examined in isolated, perfused mouse kidneys the metabolism of 5'-AMP (applied to the lumen of the renal vasculature via intrarenal artery administration) to adenosine by measuring renal venous levels of 5'-AMP, adenosine, and inosine (adenosine metabolite) by mass spectrometry. In one study, we compared 5'-AMP metabolism in naive CD73+/+ (wild-type, n = 16) vs. CD73-/- (knockout, n = 16) kidneys; and in a second study, we compared 5'-AMP metabolism in CD73+/+ (n = 9) vs. CD73-/- (n = 8) kidneys pretreated with levamisole (1 mmol/l; TNAP inhibitor). In naive kidneys, 5'-AMP increased renal venous 5'-AMP, adenosine, and inosine, and these responses were similar in CD73+/+ vs. CD73-/- kidneys. Levamisole per se did not inhibit renovascular 5'-AMP metabolism; however, in the presence of levamisole, 5'-AMP increased renal venous 5'-AMP threefold more in CD73-/- vs. CD73+/+ kidneys and knockout of CD73 inhibited 5'-induced adenosine and inosine by 81 and 86%, respectively. TNAP mRNA, protein, and activity were similar in CD73+/+ vs. CD73-/- kidneys. In conclusion, CD73 and TNAP play interactive roles to metabolize luminally applied 5'-AMP in the renal vasculature such that inhibition of both is required to inhibit the production of adenosine.
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PMID:Interactive roles of CD73 and tissue nonspecific alkaline phosphatase in the renal vascular metabolism of 5'-AMP. 2499 Aug 99