1.3.3.11	3a-(2-amino-2-carboxyethyl)-4,5-dioxo-4,5,6,7,8,9-hexahydroquinoline-7,9-dicarboxylic acid + O2	synthesis of the pyrroloquinoline quinone (PQQ), that serves as prosthetic group for many bacterial enzymes	
1.3.3.11	3a-(2-amino-2-carboxyethyl)-4,5-dioxo-4,5,6,7,8,9-hexahydroquinoline-7,9-dicarboxylic acid + O2	synthesis of the pyrroloquinoline quinone (PQQ), that serves as prosthetic group for many bacterial enzymes, PQQ might also be involved in the protection against reactive oxygen species during growth under stress conditions	
1.3.3.11	6-(2-amino-2-carboxyethyl)-7,8-dioxo-1,2,3,4,5,6,7,8,-octahydroquinoline-2,4-dicarboxylate + O2	-	
1.3.3.11	6-(2-amino-2-carboxyethyl)-7,8-dioxo-1,2,3,4,7,8-hexahydroquinoline-2,4-dicarboxylate + 3 O2	-	
1.3.3.11	additional information	catalyzes the final step of PQQ formation, which involves a ring closure and an overall eight-electron oxidation of 3a-(2-amino-2-carboxyethyl)-4,5-dioxo-4,5,6,7,8,9-hexahydroquinoline-7,9-dicarboxylic acid in the absence of a redox-active metal or cofactor	
1.3.3.11	additional information	PqqC/D produces the reduced pyrroloquinoline quinone from the intermediate in vivo