Reaction: xanthoxin + NAD+ = abscisic aldehyde + NADH + H+
For diagram click here (mechanism).
Other name(s): xanthoxin oxidase; ABA2
Systematic name: xanthoxin:NAD+ oxidoreductase
Comments: Requires a molybdenum cofactor for activity. NADP+ cannot replace NAD+ and short-chain alcohols such as ethanol, isopropanol, butanol and cyclohexanol cannot replace xanthoxin as substrate [3]. Involved in the abscisic-acid biosynthesis pathway in plants, along with EC 1.2.3.14 (abscisic aldehyde oxidase), EC 1.13.11.51 (9-cis-epoxycarotenoid dioxygenase) and EC 1.14.13.93 [(+)-abscisic acid 8'-hydroxylase]. Abscisic acid is a sesquiterpenoid plant hormone that is involved in the control of a wide range of essential physiological processes, including seed development, germination and responses to stress [3].
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number: 129204-37-1
References:
1. Sindhu, R.K. and Walton, D.C. Xanthoxin metabolism in cell-free preparations from wild type and wilty mutants of tomato. Plant Physiol. 88 (1988) 178-182.
2. Schwartz, S.H., Leon-Kloosterziel, K.M., Koornneef, M. and Zeevaart, J.A. Biochemical characterization of the aba2 and aba3 mutants in Arabidopsis thaliana. Plant Physiol. 114 (1997) 161-166. [PMID: 9159947]
3. González-Guzmán, M., Apostolova, N., Bellés, J.M., Barrero, J.M., Piqueras, P., Ponce, M.R., Micol, J.L., Serrano, R. and Rodríguez, P.L. The short-chain alcohol dehydrogenase ABA2 catalyzes the conversion of xanthoxin to abscisic aldehyde. Plant Cell. 14 (2002) 1833-1846. [PMID: 12172025]