Glutamine nonenzymic

IV. Nonenzymic Formation of Pyrrolidone Carboxylic Acid from Glutamic Acid, Glutamine, and Other Compounds... 

Gilbert JB, Price VE, Greenstein IP. Effect of anions on the nonenzymic desamidation of glutamine. J. Biol. Chem. 1949 180 209-218. 

Cimino F, Anderson WB, Stadtman ER (1970) Ability of nonenzymic nitration or acetylation of E. coli glutamine synthetase to produce effects analogous to enzymic adenylylation. Proc Natl Acad Sci USA 66 564-571... 

Neither transfer of single ADPR residues by specific eukaryotic transferases nor the existence of other than ester-type linkages in ADPR protein conjugates were recognized for a number of years [24]. Now, there is increasing evidence that the eukaryotic cell possesses a rather elaborate instrumentarium of ADP-ribosylation reactions to modulate important processes. The use of mono(ADPR) groups for the covalent modification of protein provides a tool that may prove to be as versatile as poly(ADP-ribosyl)ation. In addition to the systems discussed here (alkylated cells, differentiation, tumor promotors), mono(ADP-ribosyl)ation may be involved also in the modulation of protein synthesis [8], in the response to heat shock (M. Jacobson, personal communication), and in glutamine synthesis [25]. Nonenzymic mono(ADP-ribosyl)ation reactions must also be taken into consideration whenever the functions of active (P)ADP-ribose as present in the pyridine nucleotides are studied. Finally, preliminary data may indicate that an additional way to modulate protein functions could be provided by phospho-(ADP-ribosylation) reactions. 

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