Xanthosine-5'-phosphate amidotransferase from Escherichia coli.

摘要: The purified enzyme xanthosine-5'-monophosphate (XMP) aminase from Escherichia coli strain B-96 is shown to possess catalytic activity with either glutamine or ammonia as a substrate. This enzyme, which possesses identical subunits, has the following properties: (a) pH optimum of 8.3 for both and amidotransferase; (b) an apparent K-m NH3 1 mM; (c) amidotransferase that approximately 2 times more active than aminase; (d) linear relationship between velocity concentrationfor activities; (e) inhibition activities by analogue 6-diazo-5-oxo-L-norleucine, but sensitive (f) inhbiition adenosine analogue, psicofuranine, again aminase. so-called XMP E. mutant B-24-1 also been examined in crude extracts nad ammonium sulfate fractions data have obtained: preparations contain activity; same substrate requirements; optima extract are those found preparation; 2- 3-fold These demonstrate this not strictly is, fact, capable utilizing