title: [Identification of an extracellular nucleotide pyrophosphatase in the culture media of Streptomyces mediterranei ME/R 17].
abstract: An exocellular pyrophosphatase, active on the nucleotide precursors of peptidoglycans, has been found in the culture medium of Streptomyces mediterranei ME/R 17. This enzyme was separated from the DD-carboxypeptidase by batchwise adsorption on DEAE cellulose. The pyrophosphatase had no strict substrate requirements, it hydrolyzed various UDP-sugar substrates: UDP-GlcNAc, UDP-Mur NAc and UDP-MurNAc peptides, giving rise to the corresponding sugar phosphate and to UMP. The enzyme preparation also contained a 5'-nucleotidase activity and UMP was further split to give uridine. This nucleotidase activity was inhibited by potassium tetraborate. Both cytoplasmic and particulate preparations from cells of S. mediterranei also contained a pyrophosphatase activity while only the particulate fractions showed the DD-carboxypeptidase activity. The pyrophosphatase excretion was tested during the grwoth cycle. The activity of the enzyme showed a constant increase throughout the exponential growth and a stronger increase in the late exponential phase. Such a result could be correlated with a consumption of the nutrients in the culture medium, in fact a relatively poor culture medium had a strong positive effect upon the production of the exocellular pyrophosphatase.
mesh_terms: D001881:Borates / Q000494:pharmacology; D002268:Carboxypeptidases / Q000378:metabolism; D003470:Culture Media; D011755:Pyrophosphatases / Q000378:metabolism*; D013302:Streptomyces / Q000201:enzymology* / Q000254:growth & development; D014539:Uridine Diphosphate Sugars / Q000378:metabolism; D014542:Uridine Monophosphate / Q000378:metabolism
chemical_list: D001881:Borates; D003470:Culture Media; D014539:Uridine Diphosphate Sugars; D014542:Uridine Monophosphate; D002268:Carboxypeptidases; D011755:Pyrophosphatases
vernacular_title: Identification d'une nucléotide pyrophosphatase exocellulaire dans le milieu de culture de Streptomyces mediterranei ME/R 17.