5 -Nucleotidase bacterial

Becker and Hurwitz 94) have found that after infection of E. coli B with T-even bacteriophages a novel 3 -deoxynucleotidase activity appears. They purified the enzyme 2000-fold. In addition to its attack on 3 -deoxymononucleotides, the enzyme selectively removes the 3 -phos-phoryl groups from DNA. It does not attack 3 -ribonucleotides, 3 -phosphoryl groups of RNA, or 5 -phosphate esters. Like bacterial 5 -nucleotidases, this enzyme is markedly activated by Mg2+ and Co2+ and is inhibited by EDTA. The enzyme appears to be a phage-induced enzyme the activity rises early after injection with T-even phages and formation of the enzyme is blocked with chloramphenicol. 

Ammerman, J. W., and F. Azam. 1985. Bacterial 5 -nucleotidase in aquatic ecosystems A novel mechanism of phosphorus regeneration. Science 227 1338-1340. 

Arnmerman, J. W., and Azam, F. (1991a). Bacterial 5 -nucleotidase activity in estuarine and coastal marine waters Role in phosphorus regeneration. Limnol. Oceanogr. 36, 1437-1447. 

Bacterial 5 -nucleotidase activity was first noted in marine systems as a means of turning over 5 -mononucleotides, conceivably released by phosphodiesterase or exonucleolytic activity (Ammerman and Azam, 1985). Although alkaline phosphatase can hydrolyse these substrates, it can be distinguished from 5 -nucleotidase activity by its sensitivity to micromolar concentrations of phosphate 5 -nucleotidase was virtually unaffected by 100 p,M phosphate, while 80% of alkaline phosphatase activity was lost under the same conditions (Ammerman and Azam, 1991a). Further, 5 -nucleotidase was competitively inhibited by 5 -guanidyl monophosphate, but almost completely... 

The GPIs started being recognized a unique tool for membrane anchoring after first observations that bacterial phosphatidylinositol phosphoHpase C releases alkaline phosphatase, 5 -nucleotidase, and acetylchoHnesterase from various tissues in soluble form suggesting that these proteins are localized at the periphery of the cell membrane by a phosphatidylinositol-containing Hpid [3, 4]. Further studies on these and other eukaryotic proteins led to the first fuU structural elucidation of a GPI molecule, the Trypanosoma brucei variant surface glycoprotein (VSG) GPI anchor [5, 6]. 

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