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

A modification of a kinetic determination of 5'-nucleotidase (EC 3.1.3.5) activity is described. Special attention has been paid to the stabilisation of glutamate dehydrogenase (EC 1.4.1.2) by L-leucine, optimal NADH concentration and the influence of endogeneous ammonia. The optimal concentrations of the other constituents of the reagent were checked with the optimal values given in the literature. Normal values were determined. The proposed method shows a good correlation with a colorimetric reference method.
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PMID:A kinetic method for serum 5'-nucleotidase using stabilised glutamate dehydrogenase. 18 Feb 32

In model experiments using human erythrocytes, glycochenodeoxycholate caused extensive membrane damage (as judged by release of membrane phospholipid and acetylcholinesterase and by cell lysis) at approximately 10-fold lower concentrations than glycocholate. Chenodeoxycholate feeding had no effect upon the total protein, bile salt or phospholipid concentration of rat bile, although evidence is presented to suggest an expansion of the bile salt pool occurred. Rats fed chenodeoxycholate showed a dose-dependent enrichment of this bile acid in bile; this occurred mainly at the expense of cholate. Chenodeoxycholate feeding resulted in an increased biliary output of the plasma membrane enzymes alkaline phosphatase and 5'-nucleotidase; the hepatic activities of these enzymes were also increased. In contrast, the biliary output and hepatic activities of two other plasma membrane enzymes, alkaline phosphodiesterase I and L-leucine-beta-naphthylamidase, were unaffected by chenodeoxycholate feeding. A greater proportion of all four plasma membrane enzymes studied existed in bile of chenodeoxycholate-fed rats in a "soluble" form (as judged by their remaining in the supernatant on centrifugation of bile). These results are discussed in relation to the origin of plasma membrane enzymes in bile and to the potential toxicity of chenodeoxycholate and its conjugates to the membranes of the hepatobiliary system.
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PMID:Effect of chenodeoxycholate feeding upon the biliary output of plasma membrane enzymes in the rat. 608 20

To characterize the placental amino acid transport systems, L-alanine and L-leucine uptakes were studied using microvillous brush border membrane vesicles prepared from human placenta. The specific activities of alkaline phosphatase and 5'-nucleotidase in the membrane preparation were enriched 9-11 times as high as those in the homogenate. Intravesicular water (IVW) volume determined with 3-O-methyl-D-glucose was 0.59 microliters/mg protein. The saturation kinetics of L-leucine uptake by the vesicles equilibrated with Na+ gave a single set of Km (4.2mM) and Vmax (1.16 mumol/ml IVW/30s). These parameters were clearly different from those for L-alanine uptake reported previously (Asai et al.: Biochem. Int., 4:377, 1982). In the presence of an inward Na+-gradient L-leucine uptake was stimulated about 2 times, but transient accumulation was not observed differing from L-alanine uptake. Discrimination of the neutral amino acid transport systems in the presence of an inward 100mM Na+-gradient revealed that the relative contributions of A, ASC and L systems, and simple diffusion were 55, 20, 15 and 10% for L-alanine, and 45, 0, 15 and 40% for L-leucine, respectively. The results indicate that the neutral amino acid transport systems in the human placental microvillous membranes are clearly different between L-alanine and L-leucine.
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PMID:[Studies on the amino acid transport systems in the human placenta--L-alanine and L-leucine uptake by microvillous brush border membrane vesicles]. 629 24