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)

Plasma membrane vesicles were purified from rat aortic myocytes by centrifugation in a discontinuous sucrose gradient. Vesicles were prepared in the presence or absence of five proteinase inhibitors (aprotinin, benzamidine, leupeptin, pepstatin A and phenylmethylsulfonyl fluoride). The proteinase inhibitors decreased the Vmax by 3.4-fold and had no effect on the Km for Ca2+ of Na+ gradient-dependent 45Ca2+ influx. The proteinase inhibitors had no direct effect on exchange activity, and they had no effect on membrane purity as indicated by 5'-nucleotidase activity. Removing the proteinase inhibitors or adding trypsin or chymotrypsin increased exchange activity approx. 2-fold. The Vmax of exchange activity in intact aortic myocytes is approx. 10-fold higher than the Vmax in plasma membrane vesicles prepared in the presence of proteinase inhibitors. Exchange activity in plasma membrane vesicles is only a sixtieth of the expected value, because the vesicles have approx. 7-fold higher 5'-nucleotidase activity and approx. 6-fold higher specific exchange activity than the crude homogenate. The large loss of exchange activity may be caused by a change in a regulatory domain of the exchanger because endogenous proteolysis restores some of the activity lost during vesicle preparation.
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PMID:Sodium-calcium exchange in membrane vesicles from aortic myocytes: stimulation by endogenous proteolysis masks inactivation during vesicle preparation. 189 60

Sarcolemmal vesicles prepared by a new procedure from bovine tracheal smooth muscle were found to have a Na-Ca exchange activity that is significantly higher than that reported for different preparations from other types of smooth muscle. The exchange process system co-purified with 5'-nucleotidase, a plasma membrane marker enzyme, and was significantly enriched (over 100-fold) compared to mitochondria (cytochrome-c oxidase) but only slightly enriched (4-fold) compared to sarcoplasmic reticulum (NADPH-cytochrome-c reductase). The Na+ dependence of Ca2+ transport was demonstrated through both uptake and efflux procedures. The uptake profile with respect to Ca2+ was monotonic with a linear vo VS. vo.S-1 plot. The resultant Km of Ca2+ from the airway sarcolemmal vesicles (20 microM) was similar in magnitude to the Km of cardiac sarcolemmal vesicles (30 microM). Tracheal vesicles demonstrated a Vmax of 0.3-0.5 nmol.mg-1.s-1 which is significantly higher than that reported in preparations from other smooth muscle types. Furthermore, two processes found to stimulate cardiac Na-Ca exchange, pretreatment with either a mixture of dithiothreitol and Fe2+ or with chymotrypsin, were ineffective on the tracheal smooth muscle. Thus, the Na-Ca exchanger identified in tracheal smooth muscle appears to be different from that observed in cardiac muscle, implying that regulation of this activity may also be different.
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PMID:Sodium-calcium exchange in sarcolemmal vesicles from tracheal smooth muscle. 282 16

Duodenal aspirates were obtained before, during, and after stimulation with secretin-cholecystokinin in 26 patients whose pancreatic function was classified as normal, moderately reduced, or severely reduced. The activities of gamma-glutamyltransferase (GGT), alkaline phosphatase (ALP), and 5'-nucleotidase (5NT) in the aggregated duodenal aspirate collected 10-40 min after stimulation showed marked overlap between the functional groups and lacked diagnostic value. For all three enzymes, the peak response occurred later in the severely impaired group than in those with normal pancreatic function. The three enzymes showed significant positive correlations with each other, and were negatively correlated with the output of trypsin and chymotrypsin and, in contrast with these proteolytic enzymes which were reduced in pancreatic disease, GGT, ALP, and 5NT all tended to increase with pancreatic disease. Contrary to a previous report, GGT did not serve as a useful index of pancreatic cancer in this study.
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PMID:Activities of gamma-glutamyl transferase, 5'-nucleotidase and alkaline phosphatase in human duodenal aspirate. 287 69

Purified virions of HVJ (Sendai virus) were found to contain a guanylate cyclase activity that converts GTP to cyclic GMP. Activities of adenylate cyclase and 5'-nucleotidase which are frequently used as marker enzymes of cell membranes were not detected in the virus. Guanylate cyclase and virion-associated activities, neuraminidase and hemagglutinin, were co-purified during a purification of virions. Guanylate cyclase activity was not detected without disruption of the virions with a detergent, Triton X-100 or Nonident P-40. Treatment of intact HVJ with a proteolytic enzyme, trypsin or chymotrypsin, destroyed both neuraminidase and hemagglutinin; however, most of the guanylate cyclase ws retained. Guanylate cyclase activity was found in fractions containing nucleocapsids after sucrose density gradient centrifugation of disrupted virions. These results indicated that the enzyme was tightly bound to cores of HVJ and, therefore, its presence could not be explained by binding of host cell enzyme to the surface of virions. Properties of the virus-derived enzyme and particulate fractions of host cell homogenates were similar. Antiserum against nucleocapsids of HVJ inhibited guanylate cyclase activity of HVJ and particulate fractions of cells such as chorioallantoic membrane and rat liver, while soluble guanylate cyclase was not inhibited by antiserum. The biological significance and origin of guanylate cyclase found in HVJ are obscure and await further study.
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PMID:Evidence for guanylate cyclase activity associated with hemagglutinating virus of Japan (Sendai virus). 610 29

A zymogen granule fraction has been isolated from rat pancreas, and its purity has been assessed by biochemical and morphological criteria. Specific activities of two marker enzymes, amylase and chymotrypsin, are increased by 4.6 and 5.4-fold, respectively, as compared to the homogenate. The purified fraction is devoid of detectable RNA, DNA and 5'-nucleotidase, glucose-6-phosphatase, and cytochrome c oxidase activities. Electron micrographs confirm the absence of mitochondria, lysosomes, and rough endoplasmic reticulum fragments. Zymogen granule membranes were isolated from this fraction on a sucrose gradient following lysis in alkaline buffer. Secretory contaminants were efficiently removed from the membranes as indicated by experiments in which labeled secretory proteins were added during the isolation procedure and secondly by measuring residual levels of amylase and chymotrypsin. Three enzyme activities were found in the membranes: thiamine pyrophosphatase, ATP-diphosphohydrolase, and low levels of acid phosphatase. Membrane proteins were solubilized by urea-Triton X-100 and separated in double-dimension (isoelectric focusing and sodium dodecyl sulfate-polyacrylamide gel electrophoresis). Isoelectric point and molecular weight of each protein band were determined.
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PMID:Isolation of zymogen granules from rat pancreas and characterization of their membrane proteins. 629 Feb 20