EC 3.5.4.42     
Accepted name: N-isopropylammelide isopropylaminohydrolase
Reaction: N-isopropylammelide + H2O = cyanuric acid + isopropylamine
Glossary: N-isopropylammelide = 2,4-dihydroxy-6-(isopropylamino)-1,3,5-triazine
cyanuric acid = s-triazine-2,4,6-triol
Other name(s): atzC (gene name)
Systematic name: N-isopropylammelide isopropylaminohydrolase
Comments: Requires Zn2+. This bacterial enzyme is involved in degradation of the herbicide atrazine. It can hydrolyse other N-substituted amino dihydroxy-s-triazine molecules, and prefers substrates with linear N-alkyl groups to those with branched alkyl groups.
References:
1.  Sadowsky, M.J., Tong, Z., de Souza, M. and Wackett, L.P. AtzC is a new member of the amidohydrolase protein superfamily and is homologous to other atrazine-metabolizing enzymes. J. Bacteriol. 180 (1998) 152–158. [PMID: 9422605]
2.  Shapir, N., Osborne, J.P., Johnson, G., Sadowsky, M.J. and Wackett, L.P. Purification, substrate range, and metal center of AtzC: the N-isopropylammelide aminohydrolase involved in bacterial atrazine metabolism. J. Bacteriol. 184 (2002) 5376–5384. [PMID: 12218024]
3.  Balotra, S., Warden, A.C., Newman, J., Briggs, L.J., Scott, C. and Peat, T.S. X-ray structure and mutagenesis studies of the N-isopropylammelide isopropylaminohydrolase, AtzC. PLoS One 10:e0137700 (2015). [PMID: 26390431]
[EC 3.5.4.42 created 2000 as EC 3.5.99.4, transferred 2016 to EC 3.5.4.42]
 
 
EC 3.5.4.43     
Accepted name: hydroxydechloroatrazine ethylaminohydrolase
Reaction: hydroxyatrazine + H2O = N-isopropylammelide + ethylamine
Glossary: hydroxyatrazine = 4-(ethylamino)-6-(isopropylamino)-1,3,5-triazin-2-ol
N-isopropylammelide = 6-(isopropylamino)-1,3,5-triazine-2,4-diol
Other name(s): atzB (gene name); 2,4-dihydroxy-6-(isopropylamino)-1,3,5-triazine ethylaminohydrolase
Systematic name: hydroxyatrazine ethylaminohydrolase
Comments: Contains Zn2+. This bacterial enzyme is involved in degradation of the herbicide atrazine. The enzyme has a broad substrate range, and requires a monohydroxylated s-triazine ring with a minimum of one primary or secondary amine substituent and either a chloride or amine leaving group. It catalyses both deamination and dechlorination reactions.
References:
1.  Boundy-Mills, K.L., de Souza, M.L., Mandelbaum, R.T., Wackett, L.P. and Sadowsky, M.J. The atzB gene of Pseudomonas sp. strain ADP encodes the second enzyme of a novel atrazine degradation pathway. Appl. Environ. Microbiol. 63 (1997) 916–923. [PMID: 9055410]
2.  Seffernick, J.L., Aleem, A., Osborne, J.P., Johnson, G., Sadowsky, M.J. and Wackett, L.P. Hydroxyatrazine N-ethylaminohydrolase (AtzB): an amidohydrolase superfamily enzyme catalyzing deamination and dechlorination. J. Bacteriol. 189 (2007) 6989–6997. [PMID: 17660279]
[EC 3.5.4.43 created 2000 as EC 3.5.99.3, transferred 2016 to EC 3.5.4.43]
 
 
EC 3.5.99.3      
Transferred entry: hydroxydechloroatrazine ethylaminohydrolase. Now EC 3.5.4.43, hydroxydechloroatrazine ethylaminohydrolase
[EC 3.5.99.3 created 2000, deleted 2016]
 
 
EC 3.5.99.4      
Transferred entry: N-isopropylammelide isopropylaminohydrolase. Now EC 3.5.4.42, N-isopropylammelide isopropylaminohydrolase
[EC 3.5.99.4 created 2000, deleted 2016]