Xanthophyll cycle Xanthophyll

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the xanthophyll cycle


the xanthophyll cycle involves enzymatic removal of epoxy groups xanthophylls (e.g. violaxanthin, antheraxanthin, diadinoxanthin) create so-called de-epoxidised xanthophylls (e.g. diatoxanthin, zeaxanthin). these enzymatic cycles found play key role in stimulating energy dissipation within light-harvesting antenna proteins non-photochemical quenching- mechanism reduce amount of energy reaches photosynthetic reaction centers. non-photochemical quenching 1 of main ways of protecting against photoinhibition. in higher plants, there 3 carotenoid pigments active in xanthophyll cycle: violaxanthin, antheraxanthin, , zeaxanthin. during light stress, violaxanthin converted zeaxanthin via intermediate antheraxanthin, plays direct photoprotective role acting lipid-protective anti-oxidant , stimulating non-photochemical quenching within light-harvesting proteins. conversion of violaxanthin zeaxanthin done enzyme violaxanthin de-epoxidase, while reverse reaction performed zeaxanthin epoxidase.


in diatoms , dinoflagellates, xanthophyll cycle consists of pigment diadinoxanthin, transformed diatoxanthin (diatoms) or dinoxanthin (dinoflagellates) under high-light conditions.


wright et al. (feb 2011) found that, increase in zeaxanthin appears surpass decrease in violaxanthin in spinach , commented discrepancy explained synthesis of zeaxanthin beta-carotene , noted further study required explore hypothesis.








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