Is Mycobacterium phlei Glutamotransferase endowed with Glutamine Synthetase Activity?

Abstract

IN a previous paper1 we reported the finding of glutamotransferase (an enzyme catalysing the transfer of the γ-glutamyl residue of glutamine to hydroxylamine)2 in cell-free extracts of M. phlei. The enzyme required the presence of manganese ions, which could not be substituted by magnesium ions. No glutamine synthetase (an enzyme catalysing the synthesis of glutamine from glutamic acid and ammonia) activity was found in the M. phlei preparations, when tested in the presence of magnesium ions under conditions optimal for this enzyme in preparations of bacterial2, plant3 and animal4 origin. The M. phlei extracts possessed only traces, if any, of glutaminase activity and did not hydrolyse glutamohydroxamic acid at all. On the other hand, these preparations showed very high asparaginase activity, lacking any asparto-transferase and asparagine synthetase activities. Aspartohydroxamic acid was very strongly hydrolysed by the M. phlei extracts; however, this activity. We have, therefore, concluded that in M. phlei the reactions of transfer, synthesis and hydrolysis are due to the action of different enzymes.

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References

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HALPERN, Y., GROSSOWICZ, N. Is Mycobacterium phlei Glutamotransferase endowed with Glutamine Synthetase Activity?. Nature 190, 812 (1961). https://doi.org/10.1038/190812a0

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