IUBMB Enzyme Nomenclature


Accepted name: (+)-abscisic acid 8'-hydroxylase

Reaction: (+)-abscisate + NADPH + H+ + O2 = 8'-hydroxyabscisate + NADP+ + H2O

For diagram click here.

Other name(s): (+)-ABA 8'-hydroxylase; ABA 8'-hydroxylase

Systematic name: abscisate,NADPH:oxygen oxidoreductase (8'-hydroxylating)

Comments: A heme-thiolate protein (P-450). 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. Other enzymes involved in the abscisic-acid biosynthesis pathway are EC (xanthoxin dehydrogenase), EC (abscisic aldehyde oxidase) and EC (9-cis-epoxycarotenoid dioxygenase).

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]

[EC created 2005]

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