FAD is a further essential cofactor of the NAD(P)H and O2‐dependent zeaxanthin‐epoxidase
- 27 November 1995
- journal article
- Published by Wiley in FEBS Letters
- Vol. 376 (1-2), 45-48
- https://doi.org/10.1016/0014-5793(95)01243-9
Abstract
In chloroplasts of plants the xanthophyll cycle is suggested to function as a protection mechanism against photodamage. Two enzymes catalyze this cycle. One of them, violaxanthin de-epoxidase, transforms violaxanthin (Vio) to zeaxanthin (Zea) via antheraxanthin (Anth) and is bound to the lumenal surface of the thylakoid vesicles, when being in its active state. The other enzyme, Zea-epoxidase, is responsible for the backward reaction (Zea-->Anth-->Vio) and is active at the stromal side of the thylakoid. For the epoxidation of Zea this enzyme requires NAD(P)H and O2 as cosubstrates. Using isolated thylakoid membranes we found that FAD enhances the epoxidase activity (decrease of apparent Km for NAD(P)H and two-fold increase of Vmax). The flavin functions as a third cofactor which is partially lost during the isolation procedure of thylakoids. Other flavins, such as FMN or riboflavin are without effect. The involvement of FAD in the enzymatic reaction is also demonstrated by the inhibitory action of diphenyleneiodoniumchloride (DPI) (IC50 = 2.3 microM), a compound that blocks the reoxidation of reduced flavins within enzymes. The Zea-epoxidase is a multi-component enzyme system which can be classified as FAD-containing, NAD(P)H- and O2-dependent monooxygenase that is able to epoxidize 3-hydroxy beta-ionone rings of xanthophylls in the 5,6 position.Keywords
This publication has 34 references indexed in Scilit:
- Chlorophyll a/b-Binding Proteins, Pigment Conversions, and Early Light-Induced Proteins in a Chlorophyll b-less Barley MutantPlant Physiology, 1995
- Analysis of the Pigment Stoichiometry of Pigment-Protein Complexes from Barley (Hordeum vulgare) (The Xanthophyll Cycle Intermediates Occur Mainly in the Light-Harvesting Complexes of Photosystem I and Photosystem II)Plant Physiology, 1995
- Involvement of xanthophyll pigments in regulation of light-driven excitation quenching in light-harvesting complex of Photosystem IIBiochimica et Biophysica Acta (BBA) - Bioenergetics, 1994
- The protective function of the xanthophyll cycle in photosynthesisFEBS Letters, 1994
- Affinity probing of flavin binding sites. 1. Covalent attachment of 8-(methylsulfonyl)FAD to pig heart lipoamide dehydrogenaseBiochemistry, 1994
- LHCII, the major light-harvesting pigment-protein complex is a zeaxanthin epoxidaseBiochimica et Biophysica Acta (BBA) - Bioenergetics, 1993
- Purification, properties, and oxygen reactivity of p-hydroxybenzoate hydroxylase from Pseudomonas aeruginosaBiochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology, 1989
- Enzymatische Baeyer‐Villiger‐Oxidationen durch flavinabhängige MonooxygenasenAngewandte Chemie, 1988
- The effects of dithiothreitol on violaxanthin de-epoxidation and absorbance changes in the 500-nm regionBiochimica et Biophysica Acta (BBA) - Bioenergetics, 1972
- Dark incorporation of 18O2 into antheraxanthin by bean leafBiochimica et Biophysica Acta (BBA) - Biophysics including Photosynthesis, 1965