Hydrolyzes 1-carboxybiuret to urea-1,3-dicarboxylate and NH(3). 1-carboxybiuret + H2O = NH4(+) + urea-1,3-dicarboxylate kcat is 15.5 sec(-1) with 1-carboxybiuret as substrate. kcat is 9.4 sec(-1) with 1-nitrobiuret as substrate. kcat is 7 sec(-1) with 1-carboxymalonamide as substrate. kcat is 19 sec(-1) with succinamate as substrate. Xenobiotic degradation; atrazine degradation. Heterotetramer consisting of 2 AtzE and 2 AtzG subunits. Belongs to the amidase family. Was originally thought to use biuret as substrate (PubMed:11544232). But new evidence has shown that 1-carboxybiuret is the real substrate. The error occurred since 1-carboxybiuret hydrolyzes spontaneously to biuret (PubMed:29523689).