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2012 | 59 | 1 |
Tytuł artykułu

Zeaxanthin epoxidation - an in vitro approach

Warianty tytułu
Języki publikacji
EN
Abstrakty
EN
Zeaxanthin epoxidase (ZE) is an enzyme operating in the violaxanthin cycle, which is involved in photoprotective mechanisms. In this work model systems to study zeaxanthin (Zx) epoxidation were developed. Two assay systems are presented in which epoxidation of Zx was observed. In these assays two mutants of Arabidopsis thaliana which have active only one of the two xanthophyll cycle enzymes were used. The npq1 mutant possesses an active ZE and is thus able to convert Zx to violaxanthin (Vx) but the violaxanthin de-epoxidase (VDE) is inactive, so that Vx cannot be converted to Zx. The other mutant, npq2, possesses an active VDE and can convert exogenous Vx to Zx under strong light conditions but reverse reaction is not possible. The first assay containing thylakoids from npq1 and npq2 mutants of A. thaliana gave positive results and high efficiency of epoxidation reaction was observed. The amount of Zx was reduced by 25%. To optimize high efficiency of epoxidation reaction additional factors facilitating both fusion of the two types of thylakoids and incorporation of Zx to their membranes were also studied. The second kind of assay contained npq1 mutant thylakoids of A. thaliana supplemented with exogenous Zx and monogalactosyldiacylglycerol (MGDG). Experiments with different proportions of Zx and MGDG showed that their optimal ratio is 1:60. In such system, due to epoxidation, the amount of Zx was reduced by 38% of its initial level. The in vitro systems of Zx epoxidation described in this paper enable analysis some properties of the ZE without necessity of its isolation.
Słowa kluczowe
Wydawca
-
Rocznik
Tom
59
Numer
1
Opis fizyczny
p.105-107,fig.,ref.
Twórcy
autor
  • Department of Plant Physiology and Biochemistry, Jagiellonian University, Krakow, Poland
autor
autor
autor
Bibliografia
  • Arnon DI (1949) Copper enzymes in isolated chloroplasts. Polyphenoloxidase in Beta vulgaris. Plant Physiol 24: 1-15. 
  • K. Büch, H. Stransky, A. Hager (1995) FAD is a further essential cofactor of the NAD(P)H and O2-dependent zeaxanthin epoxidase. FEBS Letters 376: 45-48. 
  • Garcia-Plazaola JI, Matsubara S, Osmond CB (2007) The lutein epoxide cycle in higher plants: its relationships to other xanthophyll cycles and possible functions. Funct Plant Biol 34: 759-773.
  • Goss R, Lepetit B, Wilhelm C (2006) Evidence for a rebinding of antheraxanthin to the light-harvesting complex during the epoxidation reaction of the violaxanthin cycle. J Plant Physiol 163: 585-590. 
  • Hager A, Holocher K (1994) Localization of the xanthophyll-cycle enzyme violaxanthin de-epoxidase within the thylakoid lumen and abolition of its mobility by a (light-dependent) pH decrease. Planta 192: 581-589.
  • Havaux M, Bonfils JP, Lütz C, Niyogi KK (2000) Photodamage of the photosynthetic apparatus and its dependence on the leaf developmental stage in the npq1 Arabidopsis mutant deficient in the xanthophyll cycle enzyme violaxanthin deepoxidase. Plant Physiol 124: 273-284. 
  • Jahns P, Latowski D, Strzałka K (2009) Mechanism and regulation of the violaxanthin cycle: the role of antenna proteins and membrane lipids. Biochim Biophys Acta 1787: 3-14. 
  • Latowski D, Ǻkerlund HE, Strzałka K (2004) Violaxanthin de-epoxidase, the xanthophyll cycle enzyme, requires lipid inverted hexagonal structures for its activity. Biochemistry 43: 4417-4420. 
  • Latowski D, Kruk J, Burda K, Skrzynecka-Jaskier M, Kostecka-Gugała A, Strzałka K (2002) Kinetics of violaxanthin de-epoxidation by violaxanthin de-epoxidase, a xanthophyll cycle enzyme, is regulated by membrane fluidity in model lipid bilayers. Eur J Biochem 269: 4656-4665. 
  • Siefermann D, Yamamoto HY (1975) Light-induced de-epoxidation of violaxanthin in lettuce chloroplasts IV. The effects of electron-transport conditions on violaxanthin availability. Biochim Biophys Acta 387: 149-58. 
  • Yamamoto HY, Higashi RM (1978) Violaxanthin de-epoxidase. Lipid composition and substrate specificity. Arch Biochem Biophys 190: 514-522. 
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