Glutamylsulfamoyladenosine and pyroglutamylsulfamoyladenosine are competitive inhibitors of E. coli glutamyl-tRNA synthetase.

5'-O-[N-(L-glutamyl)-sulfamoyl] adenosine is a potent competitive inhibitor of E. coli glutamyl-tRNA synthetase with respect to glutamic acid (K(i) = 2.8 nM) and is the best inhibitor of this enzyme. It is a weaker inhibitor of mammalian glutamyl-tRNA synthetase (K(i) = 70 nM). The corresponding 5'-O-[N-(L-pyroglutamyl)-sulfamoyl] adenosine is a weak inhibitor (K(i) = 15 microM) of the E. coli enzyme.