9-cis-epossicarotenoid diossigenasi

La 9-cis-epossicarotenoid diossigenasi è un enzima appartenente alla classe delle ossidoreduttasi, che catalizza la seguente reazione:(1) a 9-cis-epoxycarotenoid + O2 2-cis,4-trans-xanthoxin + a 12'-apo-carotenal;;(2) 9-cis-violaxanthin + O2 2-cis,4-trans-xanthoxin + (3S,5R,6S)-5,6-epoxy-3-hydroxy-5,6-dihydro-12'-apo-ß-caroten-12'-al;;(3) 9'-cis-neoxanthin + O2 2-cis,4-trans-xanthoxin + (3S,5R,6R)-5,6-dihydroxy-6,7-didehydro-5,6-dihydro-12'-apo-ß-caroten-12'-al Requires iron(II). Acts on 9-cis-violaxanthin and 9'-cis-neoxanthin but not on the all-trans isomers [2,3]. In vitro, it will cleave 9-cis-zeaxanthin. Catalyses the first step of abscisic-acid biosynthesis from carotenoids in chloroplasts, in response to water stress. The other enzymes involved in the abscisic-acid biosynthesis pathway are <a href="query.php?name=1.1.1.288&search=search_some&es=on" target="new">EC 1.1.1.288</a> (xanthoxin dehydrogenase), <a href="query.php?name=1.2.3.14&search=search_some&es=on" target="new">EC 1.2.3.14</a> (abscisic-aldehyde oxidase) and <a href="query.php?name=1.14.13.93&search=search_some&es=on" target="new">EC 1.14.13.93</a> [(+)-abscisic acid 8'-hydroxylase].
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