The Enzyme Database

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Accepted name: (+)-abscisic acid 8′-hydroxylase
Reaction: (+)-abscisate + [reduced NADPH—hemoprotein reductase] + O2 = 8′-hydroxyabscisate + [oxidized NADPH—hemoprotein reductase] + H2O
For diagram of abscisic-acid biosynthesis, click here
Other name(s): (+)-ABA 8′-hydroxylase; ABA 8′-hydroxylase; CYP707A1 (gene name)
Systematic name: abscisate,[reduced NADPH—hemoprotein reductase]:oxygen oxidoreductase (8′-hydroxylating)
Comments: A cytochrome P-450 (heme-thiolate) protein found in plants. Catalyses the first step in the oxidative degradation of abscisic acid and is considered to be the pivotal enzyme in controlling the rate of degradation of this plant hormone [1]. CO inhibits the reaction, but its effects can be reversed by the presence of blue light [1]. The 8′-hydroxyabscisate formed can be converted into (–)-phaseic acid, most probably spontaneously.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 153190-37-5
1.  Cutler, A.J., Squires, T.M., Loewen, M.K. and Balsevich, J.J. Induction of (+)-abscisic acid 8′ hydroxylase by (+)-abscisic acid in cultured maize cells. J. Exp. Bot. 48 (1997) 1787–1795.
2.  Krochko, J.E., Abrams, G.D., Loewen, M.K., Abrams, S.R. and Cutler, A.J. (+)-Abscisic acid 8′-hydroxylase is a cytochrome P450 monooxygenase. Plant Physiol. 118 (1998) 849–860. [PMID: 9808729]
3.  Saito, S., Hirai, N., Matsumoto, C., Ohigashi, H., Ohta, D., Sakata, K. and Mizutani, M. Arabidopsis CYP707As encode (+)-abscisic acid 8′-hydroxylase, a key enzyme in the oxidative catabolism of abscisic acid. Plant Physiol. 134 (2004) 1439–1449. [PMID: 15064374]
[EC created 2005 as EC, transferred 2018 EC]

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